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/api/v1/users.py

@@ -88,10 +88,14 @@ def update_user(
 
     # Only superusers can change is_superuser and is_active
     if not current_user.is_superuser:
-        if user_in.is_superuser is not None or user_in.is_active is not None:
+        if (
+            user_in.is_superuser is not None
+            or user_in.is_active is not None
+            or user_in.permissions is not None
+        ):
             raise HTTPException(
                 status_code=status.HTTP_403_FORBIDDEN,
-                detail="Only admins can change user status"
+                detail="Only admins can change user status or permissions"
             )
 
     user = crud.user.update(db, db_obj=user, obj_in=user_in)