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>

app/templates_config.py

@@ -21,10 +21,10 @@ from fastapi.templating import Jinja2Templates
 from jinja2 import ChoiceLoader, FileSystemLoader
 
 from app.utils.i18n import (
+    DEFAULT_LANGUAGE,
     LANGUAGE_FLAGS,
     LANGUAGE_NAMES,
     SUPPORTED_LANGUAGES,
-    DEFAULT_LANGUAGE,
     create_translation_context,
 )