Refactor settings system and improve context initialization

Backend:
- Add type validation and coercion for settings API
- Implement SettingStorage and SettingType in registry
- Improve CRUD operations for settings

Frontend:
- Refactor Theme, Language, Sidebar, ViewMode contexts
- Simplify admin components (GeneralTab, SettingsTab, UsersTab)
- Add new settings endpoints to API client
- Improve App initialization flow

Infrastructure:
- Update Dockerfile and docker-compose.yml
- Add .dockerignore
- Update Makefile and README

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/crud/base.py

@@ -71,7 +71,7 @@ class CRUDBase(Generic[ModelType, CreateSchemaType, UpdateSchemaType]):
 
     def delete(self, db: Session, *, id: Any) -> ModelType:
         """Delete a record."""
-        obj = db.query(self.model).get(id)
+        obj = db.get(self.model, id)
         db.delete(obj)
         db.commit()
         return obj