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/domain/entities/threat_actor.py

@@ -7,7 +7,10 @@ from __future__ import annotations
 
 import uuid
 from dataclasses import dataclass, field
-from typing import Any
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from app.models.threat_actor import ThreatActor as ThreatActorORM
 
 
 @dataclass
@@ -63,7 +66,7 @@ class ThreatActorEntity:
         return round(len(self.covered_techniques) / len(self.techniques) * 100, 1)
 
     @classmethod
-    def from_orm(cls, orm: Any) -> ThreatActorEntity:
+    def from_orm(cls, orm: ThreatActorORM) -> ThreatActorEntity:
         techs: list[ThreatActorTechniqueRef] = []
         for tat in getattr(orm, "techniques", None) or []:
             technique = getattr(tat, "technique", None)