refactor(types): add comprehensive type annotations across backend Python codebase

Enable ANN rules in ruff.toml (flake8-annotations) and resolve all 221 violations:

ANN201/ANN202 — return types on 168 public/private functions:
- All 28 FastAPI routers: endpoints annotated with dict/list/specific schema/
  StreamingResponse/FileResponse/JSONResponse as appropriate
- main.py: lifespan→AsyncGenerator[None,None], exception handlers→JSONResponse
- database.py: get_db→Generator[Session,None,None], proxy methods→correct types
- middleware/request_context.py: dispatch→Response with Callable call_next type

ANN001/ANN002/ANN003 — 32 missing argument types:
- seed_demo.py: all db parameters typed as Session
- domain/unit_of_work.py: __aexit__ exc_type/exc_val/exc_tb typed with TracebackType
- services: audit_service user_id→UUID|None, heatmap_service query/model/builder,
  notification_service test→Test, tempo_service test→Test/user→User,
  test_workflow_service test_id→UUID, campaign_crud **fields→object,
  test_crud **fields→object (4 sites)

ANN401 — 16 Any usages resolved:
- Domain entities (campaign/technique/threat_actor/test_entity): replaced Any with
  actual ORM types via TYPE_CHECKING guards to avoid circular imports
- detection_rule_service: test_id/detection_rule_id/evaluator_id→UUID
- score_cache: kept Any with # noqa: ANN401 (genuinely generic cache)
- jira_service/tempo_service: kept Any with # noqa: ANN401 (lazy optional deps)
- d3fend_import_service: _to_str(v: Any) kept with # noqa: ANN401

ANN204/ANN205/ANN206 — special/static/class methods:
- database.py proxy __call__/__getattr__: *args: object/**kwargs: object
- schemas/test.py model_validate: obj→object, **kwargs→object
- sa_technique_repository._int_type→type

All 439 unit tests pass. ruff check app/ → All checks passed!

backend/app/services/score_cache.py

@@ -10,12 +10,14 @@ stale data does not persist longer than ``CACHE_TTL`` seconds.
 import time
 from typing import Any, Optional
 
+from sqlalchemy.orm import Session
+
 CACHE_TTL = 300  # 5 minutes
 
 _cache: dict[str, dict[str, Any]] = {}
 
 
-def get(key: str) -> Optional[Any]:
+def get(key: str) -> Optional[Any]:  # noqa: ANN401  # generic cache returns whatever was stored
     """Return cached value if present and not expired, else None."""
     entry = _cache.get(key)
     if entry is None:
@@ -26,7 +28,7 @@ def get(key: str) -> Optional[Any]:
     return entry["data"]
 
 
-def put(key: str, data: Any) -> None:
+def put(key: str, data: Any) -> None:  # noqa: ANN401  # generic cache accepts any serialisable value
     """Store *data* under *key* with the current timestamp."""
     _cache[key] = {"data": data, "ts": time.time()}
 
@@ -42,7 +44,7 @@ def invalidate(key: Optional[str] = None) -> None:
 # ── High-level helpers ────────────────────────────────────────────────
 
 
-def get_organization_score_cached(db):
+def get_organization_score_cached(db: Session) -> dict:
     """Cached wrapper around ``calculate_organization_score``."""
     from app.services.scoring_service import calculate_organization_score
 
@@ -55,7 +57,7 @@ def get_organization_score_cached(db):
     return result
 
 
-def get_operational_metrics_cached(db):
+def get_operational_metrics_cached(db: Session) -> dict:
     """Cached wrapper around operational metrics (MTTD, MTTR, efficacy)."""
     from app.services.operational_metrics_service import (
         calculate_alert_fidelity,