Initializes Fava client on startup

Initializes the Fava client with default settings when the Castle extension starts.

This ensures the client is ready to interact with Fava immediately and provides feedback if Fava is not configured correctly.

The client is re-initialized if the admin updates settings later.

__init__.py

@@ -34,7 +34,24 @@ def castle_stop():
 def castle_start():
     """Initialize Castle extension background tasks"""
     from lnbits.tasks import create_permanent_unique_task
+    from .fava_client import init_fava_client
+    from .models import CastleSettings
 
+    # Initialize Fava client with default settings
+    # (Will be re-initialized if admin updates settings)
+    defaults = CastleSettings()
+    try:
+        init_fava_client(
+            fava_url=defaults.fava_url,
+            ledger_slug=defaults.fava_ledger_slug,
+            timeout=defaults.fava_timeout
+        )
+        logger.info(f"Fava client initialized: {defaults.fava_url}/{defaults.fava_ledger_slug}")
+    except Exception as e:
+        logger.error(f"Failed to initialize Fava client: {e}")
+        logger.warning("Castle will not function without Fava. Please configure Fava settings.")
+
+    # Start background tasks
     task = create_permanent_unique_task("ext_castle", wait_for_paid_invoices)
     scheduled_tasks.append(task)