Integrate account sync with API, background tasks, and user creation

Integration Components:
1. Manual API Endpoints (admin-only):
   - POST /api/v1/admin/accounts/sync (full sync)
   - POST /api/v1/admin/accounts/sync/{account_name} (single account)

2. Scheduled Background Sync:
   - Hourly background task (wait_for_account_sync)
   - Registered in castle_start() lifecycle
   - Automatically syncs new accounts from Beancount to Castle DB

3. Auto-sync on User Account Creation:
   - Updated get_or_create_user_account() in crud.py
   - Uses sync_single_account_from_beancount() for consistency
   - Ensures receivable/payable accounts are synced when users register

Flow:
- User associates wallet → creates receivable/payable in Beancount
  → syncs to Castle DB → permissions can be granted
- Admin manually syncs → all Beancount accounts added to Castle DB
- Hourly task → catches any accounts created directly in Beancount

This ensures Beancount remains the source of truth while Castle DB
maintains metadata for permissions and user associations.

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

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

crud.py

@@ -209,18 +209,42 @@ async def get_or_create_user_account(
             logger.error(f"[FAVA ERROR] Could not check/create account in Fava: {e}", exc_info=True)
             # Continue anyway - account creation in Castle DB is still useful for metadata
 
-    # Create account in Castle DB for metadata tracking (only if it doesn't exist)
+    # Ensure account exists in Castle DB (sync from Beancount if needed)
+    # This uses the account sync module for consistency
     if not account:
-        logger.info(f"[CASTLE DB] Creating account in Castle DB: {account_name}")
-        account = await create_account(
-            CreateAccount(
-                name=account_name,
-                account_type=account_type,
-                description=f"User-specific {account_type.value} account",
-                user_id=user_id,
-            )
+        logger.info(f"[CASTLE DB] Syncing account from Beancount to Castle DB: {account_name}")
+        from .account_sync import sync_single_account_from_beancount
+
+        # Sync from Beancount to Castle DB
+        created = await sync_single_account_from_beancount(account_name)
+
+        if created:
+            logger.info(f"[CASTLE DB] Account synced from Beancount: {account_name}")
+        else:
+            logger.warning(f"[CASTLE DB] Failed to sync account from Beancount: {account_name}")
+
+        # Fetch the account from Castle DB
+        account = await db.fetchone(
+            """
+            SELECT * FROM accounts
+            WHERE user_id = :user_id AND account_type = :type AND name = :name
+            """,
+            {"user_id": user_id, "type": account_type.value, "name": account_name},
+            Account,
         )
-        logger.info(f"[CASTLE DB] Created account in Castle DB: {account_name}")
+
+        if not account:
+            logger.error(f"[CASTLE DB] Account still not found after sync: {account_name}")
+            # Fallback: create directly in Castle DB if sync failed
+            logger.info(f"[CASTLE DB] Creating account directly in Castle DB: {account_name}")
+            account = await create_account(
+                CreateAccount(
+                    name=account_name,
+                    account_type=account_type,
+                    description=f"User-specific {account_type.value} account",
+                    user_id=user_id,
+                )
+            )
     else:
         logger.info(f"[CASTLE DB] Account already exists in Castle DB: {account_name}")