Add Fava settings UI and fix race conditions in toolbar buttons

- Add Fava URL, ledger slug, and timeout settings to super admin Settings dialog
- Reinitialize Fava client when settings are updated via services.py
- Add settingsLoaded flag to prevent race conditions where wrong toolbar
  buttons appeared before isSuperUser was determined
- Remove premature Vue mount() call from permissions.js that caused
  "Cannot read properties of undefined (reading 'user')" error

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

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

services.py

@@ -18,12 +18,29 @@ async def get_settings(user_id: str) -> CastleSettings:
 
 
 async def update_settings(user_id: str, data: CastleSettings) -> CastleSettings:
+    from loguru import logger
+
+    from .fava_client import init_fava_client
+
     settings = await get_castle_settings(user_id)
     if not settings:
         settings = await create_castle_settings(user_id, data)
     else:
         settings = await update_castle_settings(user_id, data)
 
+    # Reinitialize Fava client with new settings
+    try:
+        init_fava_client(
+            fava_url=settings.fava_url,
+            ledger_slug=settings.fava_ledger_slug,
+            timeout=settings.fava_timeout,
+        )
+        logger.info(
+            f"Fava client reinitialized: {settings.fava_url}/{settings.fava_ledger_slug}"
+        )
+    except Exception as e:
+        logger.error(f"Failed to reinitialize Fava client: {e}")
+
     return settings