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/tests/contracts/test_openapi_baseline.py

@@ -0,0 +1,102 @@
+"""OpenAPI contract test.
+
+This test pins the public HTTP contract of backend-compliance. It loads the
+FastAPI app, extracts the live OpenAPI schema, and compares it against a
+checked-in baseline at ``tests/contracts/openapi.baseline.json``.
+
+Rules:
+  - Adding new paths/operations/fields → OK (additive change).
+  - Removing a path, changing a method, changing a status code, removing or
+    renaming a response/request field → FAIL. Such changes require updating
+    every consumer (admin-compliance, developer-portal, SDKs) in the same
+    change, then regenerating the baseline with:
+
+        python tests/contracts/regenerate_baseline.py
+
+    and explaining the contract change in the PR description.
+
+The baseline is missing on first run — the test prints the command to create
+it and skips. This is intentional: Phase 1 step 1 generates it fresh from the
+current app state before any refactoring begins.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from typing import Any
+
+import pytest
+
+BASELINE_PATH = Path(__file__).parent / "openapi.baseline.json"
+
+
+def _load_live_schema() -> dict[str, Any]:
+    """Import the FastAPI app and extract its OpenAPI schema.
+
+    Kept inside the function so that test collection does not fail if the app
+    has import-time side effects that aren't satisfied in the test env.
+    """
+    from main import app  # type: ignore[import-not-found]
+
+    return app.openapi()
+
+
+def _collect_operations(schema: dict[str, Any]) -> dict[str, dict[str, Any]]:
+    """Return a flat {f'{METHOD} {path}': operation} map for diffing."""
+    out: dict[str, dict[str, Any]] = {}
+    for path, methods in schema.get("paths", {}).items():
+        for method, op in methods.items():
+            if method.lower() in {"get", "post", "put", "patch", "delete", "options", "head"}:
+                out[f"{method.upper()} {path}"] = op
+    return out
+
+
+@pytest.mark.contract
+def test_openapi_no_breaking_changes() -> None:
+    if not BASELINE_PATH.exists():
+        pytest.skip(
+            f"Baseline missing. Run: python {Path(__file__).parent}/regenerate_baseline.py"
+        )
+
+    baseline = json.loads(BASELINE_PATH.read_text())
+    live = _load_live_schema()
+
+    baseline_ops = _collect_operations(baseline)
+    live_ops = _collect_operations(live)
+
+    # 1. No operation may disappear.
+    removed = sorted(set(baseline_ops) - set(live_ops))
+    assert not removed, (
+        f"Breaking change: {len(removed)} operation(s) removed from public API:\n  "
+        + "\n  ".join(removed)
+    )
+
+    # 2. For operations that exist in both, response status codes must be a superset.
+    for key, baseline_op in baseline_ops.items():
+        live_op = live_ops[key]
+        baseline_codes = set((baseline_op.get("responses") or {}).keys())
+        live_codes = set((live_op.get("responses") or {}).keys())
+        missing = baseline_codes - live_codes
+        assert not missing, (
+            f"Breaking change: {key} no longer returns status code(s) {sorted(missing)}"
+        )
+
+    # 3. Required request-body fields may not be added (would break existing clients).
+    for key, baseline_op in baseline_ops.items():
+        live_op = live_ops[key]
+        base_req = _required_body_fields(baseline_op)
+        live_req = _required_body_fields(live_op)
+        new_required = live_req - base_req
+        assert not new_required, (
+            f"Breaking change: {key} added required request field(s) {sorted(new_required)}"
+        )
+
+
+def _required_body_fields(op: dict[str, Any]) -> set[str]:
+    rb = op.get("requestBody") or {}
+    content = rb.get("content") or {}
+    for media in content.values():
+        schema = media.get("schema") or {}
+        return set(schema.get("required") or [])
+    return set()