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/routers/tests.py

@@ -126,7 +126,7 @@ def list_tests(
     limit: int = Query(50, ge=1, le=200),
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
-):
+) -> list:
     """Return a paginated list of tests, optionally filtered by state, technique, platform or creator."""
     return crud_list_tests(
         db,
@@ -156,7 +156,7 @@ def create_test(
     payload: TestCreate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_lead", "blue_lead")),
-):
+) -> TestOut:
     """Create a new test linked to an existing technique.
 
     ``created_by`` is set automatically and ``state`` defaults to *draft*.
@@ -198,7 +198,7 @@ def create_test_from_template(
     payload: TestTemplateInstantiate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_lead", "blue_lead")),
-):
+) -> TestOut:
     """Instantiate a real Test from an existing TestTemplate.
 
     The template's fields are copied into the new test as starting data.
@@ -238,7 +238,7 @@ def get_test(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
-):
+) -> TestOut:
     """Return full details for a single test, including its evidences."""
     return crud_get_test_detail(db, test_id)
 
@@ -254,7 +254,7 @@ def update_test(
     payload: TestUpdate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_lead", "blue_lead")),
-):
+) -> TestOut:
     """Update one or more fields of an existing test.
 
     Only leads or admins can update general test fields.
@@ -294,7 +294,7 @@ def update_test_classification(
     payload: TestClassificationUpdate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_role("admin")),
-):
+) -> TestOut:
     """Update the data classification label for a test (admin only)."""
     with UnitOfWork(db) as uow:
         test = crud_get_test_or_raise(db, test_id)
@@ -324,7 +324,7 @@ def update_test_red(
     payload: TestRedUpdate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_tech", "red_lead")),
-):
+) -> TestOut:
     """Red Team updates their fields (allowed in ``draft`` and ``red_executing``)."""
     update_data = payload.model_dump(exclude_unset=True)
     with UnitOfWork(db) as uow:
@@ -354,7 +354,7 @@ def update_test_blue(
     payload: TestBlueUpdate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("blue_tech", "blue_lead")),
-):
+) -> TestOut:
     """Blue Team updates their fields (allowed only in ``blue_evaluating``)."""
     update_data = payload.model_dump(exclude_unset=True)
     with UnitOfWork(db) as uow:
@@ -383,7 +383,7 @@ def start_execution(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_tech", "red_lead")),
-):
+) -> TestOut:
     """Move a test from ``draft`` to ``red_executing``."""
     test = crud_get_test_or_raise(db, test_id)
     with UnitOfWork(db) as uow:
@@ -403,7 +403,7 @@ def submit_red(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_tech", "red_lead")),
-):
+) -> TestOut:
     """Red Team finalises — move from ``red_executing`` to ``blue_evaluating``."""
     test = crud_get_test_or_raise(db, test_id)
     with UnitOfWork(db) as uow:
@@ -423,7 +423,7 @@ def submit_blue(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("blue_tech", "blue_lead")),
-):
+) -> TestOut:
     """Blue Team finalises — move from ``blue_evaluating`` to ``in_review``."""
     test = crud_get_test_or_raise(db, test_id)
     with UnitOfWork(db) as uow:
@@ -443,7 +443,7 @@ def pause_timer(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_tech", "blue_tech", "red_lead", "blue_lead")),
-):
+) -> TestOut:
     """Pause the running timer for the current phase (red_executing or blue_evaluating)."""
     test = crud_get_test_or_raise(db, test_id)
     with UnitOfWork(db) as uow:
@@ -463,7 +463,7 @@ def resume_timer(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_tech", "blue_tech", "red_lead", "blue_lead")),
-):
+) -> TestOut:
     """Resume the paused timer for the current phase."""
     test = crud_get_test_or_raise(db, test_id)
     with UnitOfWork(db) as uow:
@@ -484,7 +484,7 @@ def validate_red(
     payload: TestRedValidate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_lead")),
-):
+) -> TestOut:
     """Red Lead approves or rejects the red side of a test."""
     test = crud_get_test_with_technique(db, test_id)
     with UnitOfWork(db) as uow:
@@ -511,7 +511,7 @@ def validate_blue(
     payload: TestBlueValidate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("blue_lead")),
-):
+) -> TestOut:
     """Blue Lead approves or rejects the blue side of a test."""
     test = crud_get_test_with_technique(db, test_id)
     with UnitOfWork(db) as uow:
@@ -537,7 +537,7 @@ def reopen(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_lead", "blue_lead")),
-):
+) -> TestOut:
     """Reopen a rejected test, moving it back to ``draft``."""
     test = crud_get_test_or_raise(db, test_id)
     with UnitOfWork(db) as uow:
@@ -558,7 +558,7 @@ def update_remediation(
     payload: TestRemediationUpdate,
     db: Session = Depends(get_db),
     current_user: User = Depends(require_any_role("red_lead", "blue_lead")),
-):
+) -> TestOut:
     """Update remediation fields on a test.
 
     When ``remediation_status`` transitions to ``'completed'``, an automatic
@@ -602,7 +602,7 @@ def get_test_timeline(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
-):
+) -> list:
     """Return the chronological audit-log history for a test."""
     return crud_get_test_timeline(db, test_id)
 
@@ -617,7 +617,7 @@ def get_retest_chain(
     test_id: uuid.UUID,
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
-):
+) -> list:
     """Return the full chain of retests (original + all retests) for a test."""
     chain = wf_get_retest_chain(db, test_id)
     if not chain: