refactor: phase 0 guardrails + phase 1 step 2 (models.py split)

Squash of branch refactor/phase0-guardrails-and-models-split — 4 commits,
81 files, 173/173 pytest green, OpenAPI contract preserved (360 paths /
484 operations).

## Phase 0 — Architecture guardrails

Three defense-in-depth layers to keep the architecture rules enforced
regardless of who opens Claude Code in this repo:

  1. .claude/settings.json PreToolUse hook on Write/Edit blocks any file
     that would exceed the 500-line hard cap. Auto-loads in every Claude
     session in this repo.
  2. scripts/githooks/pre-commit (install via scripts/install-hooks.sh)
     enforces the LOC cap locally, freezes migrations/ without
     [migration-approved], and protects guardrail files without
     [guardrail-change].
  3. .gitea/workflows/ci.yaml gains loc-budget + guardrail-integrity +
     sbom-scan (syft+grype) jobs, adds mypy --strict for the new Python
     packages (compliance/{services,repositories,domain,schemas}), and
     tsc --noEmit for admin-compliance + developer-portal.

Per-language conventions documented in AGENTS.python.md, AGENTS.go.md,
AGENTS.typescript.md at the repo root — layering, tooling, and explicit
"what you may NOT do" lists. Root CLAUDE.md is prepended with the six
non-negotiable rules. Each of the 10 services gets a README.md.

scripts/check-loc.sh enforces soft 300 / hard 500 and surfaces the
current baseline of 205 hard + 161 soft violations so Phases 1-4 can
drain it incrementally. CI gates only CHANGED files in PRs so the
legacy baseline does not block unrelated work.

## Deprecation sweep

47 files. Pydantic V1 regex= -> pattern= (2 sites), class Config ->
ConfigDict in source_policy_router.py (schemas.py intentionally skipped;
it is the Phase 1 Step 3 split target). datetime.utcnow() ->
datetime.now(timezone.utc) everywhere including SQLAlchemy default=
callables. All DB columns already declare timezone=True, so this is a
latent-bug fix at the Python side, not a schema change.

DeprecationWarning count dropped from 158 to 35.

## Phase 1 Step 1 — Contract test harness

tests/contracts/test_openapi_baseline.py diffs the live FastAPI /openapi.json
against tests/contracts/openapi.baseline.json on every test run. Fails on
removed paths, removed status codes, or new required request body fields.
Regenerate only via tests/contracts/regenerate_baseline.py after a
consumer-updated contract change. This is the safety harness for all
subsequent refactor commits.

## Phase 1 Step 2 — models.py split (1466 -> 85 LOC shim)

compliance/db/models.py is decomposed into seven sibling aggregate modules
following the existing repo pattern (dsr_models.py, vvt_models.py, ...):

  regulation_models.py       (134) — Regulation, Requirement
  control_models.py          (279) — Control, Mapping, Evidence, Risk
  ai_system_models.py        (141) — AISystem, AuditExport
  service_module_models.py   (176) — ServiceModule, ModuleRegulation, ModuleRisk
  audit_session_models.py    (177) — AuditSession, AuditSignOff
  isms_governance_models.py  (323) — ISMSScope, Context, Policy, Objective, SoA
  isms_audit_models.py       (468) — Finding, CAPA, MgmtReview, InternalAudit,
                                     AuditTrail, Readiness

models.py becomes an 85-line re-export shim in dependency order so
existing imports continue to work unchanged. Schema is byte-identical:
__tablename__, column definitions, relationship strings, back_populates,
cascade directives all preserved.

All new sibling files are under the 500-line hard cap; largest is
isms_audit_models.py at 468. No file in compliance/db/ now exceeds
the hard cap.

## Phase 1 Step 3 — infrastructure only

backend-compliance/compliance/{schemas,domain,repositories}/ packages
are created as landing zones with docstrings. compliance/domain/
exports DomainError / NotFoundError / ConflictError / ValidationError /
PermissionError — the base classes services will use to raise
domain-level errors instead of HTTPException.

PHASE1_RUNBOOK.md at backend-compliance/PHASE1_RUNBOOK.md documents
the nine-step execution plan for Phase 1: snapshot baseline,
characterization tests, split models.py (this commit), split schemas.py
(next), extract services, extract repositories, mypy --strict, coverage.

## Verification

  backend-compliance/.venv-phase1: uv python install 3.12 + pip -r requirements.txt
  PYTHONPATH=. pytest compliance/tests/ tests/contracts/
  -> 173 passed, 0 failed, 35 warnings, OpenAPI 360/484 unchanged

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend-compliance/compliance/api/dsr_routes.py

@@ -7,7 +7,7 @@ Native Python/FastAPI Implementierung, ersetzt Go consent-service Proxy.
 import io
 import csv
 import uuid
-from datetime import datetime, timedelta
+from datetime import datetime, timedelta, timezone
 from typing import Optional, List, Dict, Any
 
 from fastapi import APIRouter, Depends, HTTPException, Query, Header
@@ -168,7 +168,7 @@ def _get_tenant(x_tenant_id: Optional[str] = Header(None, alias='X-Tenant-ID'))
 
 def _generate_request_number(db: Session, tenant_id: str) -> str:
     """Generate next request number: DSR-YYYY-NNNNNN"""
-    year = datetime.utcnow().year
+    year = datetime.now(timezone.utc).year
     try:
         result = db.execute(text("SELECT nextval('compliance_dsr_request_number_seq')"))
         seq = result.scalar()
@@ -275,7 +275,7 @@ async def create_dsr(
     if body.priority and body.priority not in VALID_PRIORITIES:
         raise HTTPException(status_code=400, detail=f"Invalid priority. Must be one of: {VALID_PRIORITIES}")
 
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
     deadline_days = DEADLINE_DAYS.get(body.request_type, 30)
     request_number = _generate_request_number(db, tenant_id)
 
@@ -348,7 +348,7 @@ async def list_dsrs(
         query = query.filter(DSRRequestDB.priority == priority)
     if overdue_only:
         query = query.filter(
-            DSRRequestDB.deadline_at < datetime.utcnow(),
+            DSRRequestDB.deadline_at < datetime.now(timezone.utc),
             DSRRequestDB.status.notin_(["completed", "rejected", "cancelled"]),
         )
     if search:
@@ -399,7 +399,7 @@ async def get_dsr_stats(
         by_type[t] = base.filter(DSRRequestDB.request_type == t).count()
 
     # Overdue
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
     overdue = base.filter(
         DSRRequestDB.deadline_at < now,
         DSRRequestDB.status.notin_(["completed", "rejected", "cancelled"]),
@@ -459,7 +459,7 @@ async def export_dsrs(
 
     if format == "json":
         return {
-            "exported_at": datetime.utcnow().isoformat(),
+            "exported_at": datetime.now(timezone.utc).isoformat(),
             "total": len(dsrs),
             "requests": [_dsr_to_dict(d) for d in dsrs],
         }
@@ -506,7 +506,7 @@ async def process_deadlines(
     db: Session = Depends(get_db),
 ):
     """Verarbeitet Fristen und markiert ueberfaellige DSRs."""
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
     tid = uuid.UUID(tenant_id)
 
     overdue = db.query(DSRRequestDB).filter(
@@ -714,7 +714,7 @@ async def publish_template_version(
     if not version:
         raise HTTPException(status_code=404, detail="Version not found")
 
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
     version.status = "published"
     version.published_at = now
     version.published_by = "admin"
@@ -766,7 +766,7 @@ async def update_dsr(
         dsr.internal_notes = body.internal_notes
     if body.assigned_to is not None:
         dsr.assigned_to = body.assigned_to
-        dsr.assigned_at = datetime.utcnow()
+        dsr.assigned_at = datetime.now(timezone.utc)
     if body.request_text is not None:
         dsr.request_text = body.request_text
     if body.affected_systems is not None:
@@ -778,7 +778,7 @@ async def update_dsr(
     if body.objection_details is not None:
         dsr.objection_details = body.objection_details
 
-    dsr.updated_at = datetime.utcnow()
+    dsr.updated_at = datetime.now(timezone.utc)
     db.commit()
     db.refresh(dsr)
     return _dsr_to_dict(dsr)
@@ -797,7 +797,7 @@ async def delete_dsr(
 
     _record_history(db, dsr, "cancelled", comment="DSR storniert")
     dsr.status = "cancelled"
-    dsr.updated_at = datetime.utcnow()
+    dsr.updated_at = datetime.now(timezone.utc)
     db.commit()
     return {"success": True, "message": "DSR cancelled"}
 
@@ -820,7 +820,7 @@ async def change_status(
     dsr = _get_dsr_or_404(db, dsr_id, tenant_id)
     _record_history(db, dsr, body.status, comment=body.comment)
     dsr.status = body.status
-    dsr.updated_at = datetime.utcnow()
+    dsr.updated_at = datetime.now(timezone.utc)
     db.commit()
     db.refresh(dsr)
     return _dsr_to_dict(dsr)
@@ -835,7 +835,7 @@ async def verify_identity(
 ):
     """Verifiziert die Identitaet des Antragstellers."""
     dsr = _get_dsr_or_404(db, dsr_id, tenant_id)
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
 
     dsr.identity_verified = True
     dsr.verification_method = body.method
@@ -868,9 +868,9 @@ async def assign_dsr(
     """Weist eine DSR einem Bearbeiter zu."""
     dsr = _get_dsr_or_404(db, dsr_id, tenant_id)
     dsr.assigned_to = body.assignee_id
-    dsr.assigned_at = datetime.utcnow()
+    dsr.assigned_at = datetime.now(timezone.utc)
     dsr.assigned_by = "admin"
-    dsr.updated_at = datetime.utcnow()
+    dsr.updated_at = datetime.now(timezone.utc)
     db.commit()
     db.refresh(dsr)
     return _dsr_to_dict(dsr)
@@ -888,7 +888,7 @@ async def extend_deadline(
     if dsr.status in ("completed", "rejected", "cancelled"):
         raise HTTPException(status_code=400, detail="Cannot extend deadline for closed DSR")
 
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
     current_deadline = dsr.extended_deadline_at or dsr.deadline_at
     new_deadline = current_deadline + timedelta(days=body.days or 60)
 
@@ -916,7 +916,7 @@ async def complete_dsr(
     if dsr.status in ("completed", "cancelled"):
         raise HTTPException(status_code=400, detail="DSR already completed or cancelled")
 
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
     _record_history(db, dsr, "completed", comment=body.summary)
     dsr.status = "completed"
     dsr.completed_at = now
@@ -941,7 +941,7 @@ async def reject_dsr(
     if dsr.status in ("completed", "rejected", "cancelled"):
         raise HTTPException(status_code=400, detail="DSR already closed")
 
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
     _record_history(db, dsr, "rejected", comment=f"{body.reason} ({body.legal_basis})")
     dsr.status = "rejected"
     dsr.rejection_reason = body.reason
@@ -1024,7 +1024,7 @@ async def send_communication(
 ):
     """Sendet eine Kommunikation."""
     dsr = _get_dsr_or_404(db, dsr_id, tenant_id)
-    now = datetime.utcnow()
+    now = datetime.now(timezone.utc)
 
     comm = DSRCommunicationDB(
         tenant_id=uuid.UUID(tenant_id),
@@ -1158,7 +1158,7 @@ async def update_exception_check(
     check.applies = body.applies
     check.notes = body.notes
     check.checked_by = "admin"
-    check.checked_at = datetime.utcnow()
+    check.checked_at = datetime.now(timezone.utc)
     db.commit()
     db.refresh(check)