fix(lint): auto-fix ruff violations and tune lint rules

- Auto-fixed 4,496 lint issues (import sorting, modern syntax, etc.)
- Added ignore rules for patterns intentional in this codebase:
  E402 (late imports), E712 (SQLAlchemy filters), B904 (raise from),
  SIM108/SIM105/SIM117 (readability preferences)
- Added per-file ignores for tests and scripts
- Excluded broken scripts/rename_terminology.py (has curly quotes)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/fixtures/message_fixtures.py

@@ -6,6 +6,8 @@ Note: Fixtures should NOT use db.expunge() as it breaks lazy loading.
 See tests/conftest.py for details on fixture best practices.
 """
 
+from datetime import UTC
+
 import pytest
 
 from app.modules.messaging.models import (
@@ -171,14 +173,14 @@ def test_message_with_attachment(db, test_conversation_admin_store, test_admin):
 @pytest.fixture
 def closed_conversation(db, test_admin, test_store_user, test_store):
     """Create a closed conversation."""
-    from datetime import datetime, timezone
+    from datetime import datetime
 
     conversation = Conversation(
         conversation_type=ConversationType.ADMIN_STORE,
         subject="Closed Conversation",
         store_id=test_store.id,
         is_closed=True,
-        closed_at=datetime.now(timezone.utc),
+        closed_at=datetime.now(UTC),
         closed_by_type=ParticipantType.ADMIN,
         closed_by_id=test_admin.id,
     )
@@ -314,14 +316,14 @@ def store_api_conversation(db, test_admin, test_store_user, test_store_with_stor
 @pytest.fixture
 def store_api_closed_conversation(db, test_admin, test_store_user, test_store_with_store_user):
     """Create a closed conversation for store API tests."""
-    from datetime import datetime, timezone
+    from datetime import datetime
 
     conversation = Conversation(
         conversation_type=ConversationType.ADMIN_STORE,
         subject="Store API Closed Conversation",
         store_id=test_store_with_store_user.id,
         is_closed=True,
-        closed_at=datetime.now(timezone.utc),
+        closed_at=datetime.now(UTC),
         closed_by_type=ParticipantType.ADMIN,
         closed_by_id=test_admin.id,
     )