Restructure: Move 52 files into 7 domain packages

korrektur/ zeugnis/ admin/ compliance/ worksheet/ training/ metrics/
52 shims, relative imports, RAG untouched.

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

klausur-service/backend/admin_api.py

@@ -1,33 +1,4 @@
-"""
-Admin API for NiBiS Data Management (barrel re-export)
-
-This module was split into:
-  - admin_nibis.py      (NiBiS ingestion, search, stats)
-  - admin_rag.py        (RAG upload, metrics, storage)
-  - admin_templates.py  (Legal templates ingestion, search)
-
-The `router` object is assembled here by including all sub-routers.
-Importers that did `from admin_api import router` continue to work.
-"""
-
-from fastapi import APIRouter
-
-from admin_nibis import router as _nibis_router
-from admin_rag import router as _rag_router
-from admin_templates import router as _templates_router
-
-# Re-export internal state for test importers
-from admin_nibis import (  # noqa: F401
-    _ingestion_status,
-    NiBiSSearchRequest,
-    search_nibis,
-)
-from admin_rag import _upload_history  # noqa: F401
-from admin_templates import _templates_ingestion_status  # noqa: F401
-
-# Assemble the combined router.
-# All sub-routers use prefix="/api/v1/admin", so include without extra prefix.
-router = APIRouter()
-router.include_router(_nibis_router)
-router.include_router(_rag_router)
-router.include_router(_templates_router)
+# Backward-compat shim -- module moved to admin/api.py
+import importlib as _importlib
+import sys as _sys
+_sys.modules[__name__] = _importlib.import_module("admin.api")