Fixes user account creation in Fava/Beancount

This commit fixes two critical bugs in the user account creation flow:

1. **Always check/create in Fava regardless of Castle DB status**
   - Previously, if an account existed in Castle DB, the function would
     return early without checking if the Open directive existed in Fava
   - This caused accounts to exist in Castle DB but not in Beancount
   - Now we always check Fava and create Open directives if needed

2. **Fix Open directive insertion to preserve metadata**
   - The insertion logic now skips over metadata lines when finding
     the insertion point
   - Prevents new Open directives from being inserted between existing
     directives and their metadata, which was causing orphaned metadata

3. **Add comprehensive logging**
   - Added detailed logging with [ACCOUNT CHECK], [FAVA CHECK],
     [FAVA CREATE], [CASTLE DB], and [WALLET UPDATE] prefixes
   - Makes it easier to trace account creation flow and debug issues

4. **Fix Fava filename handling**
   - Now queries /api/options to get the Beancount file path dynamically
   - Fixes "Parameter 'filename' is missing" errors with /api/source

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

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

services.py

@@ -37,19 +37,28 @@ async def get_user_wallet(user_id: str) -> UserWalletSettings:
 async def update_user_wallet(
     user_id: str, data: UserWalletSettings
 ) -> UserWalletSettings:
+    from loguru import logger
+
+    logger.info(f"[WALLET UPDATE] Starting update_user_wallet for user {user_id[:8]}")
+
     settings = await get_user_wallet_settings(user_id)
     if not settings:
+        logger.info(f"[WALLET UPDATE] Creating new wallet settings for user {user_id[:8]}")
         settings = await create_user_wallet_settings(user_id, data)
     else:
+        logger.info(f"[WALLET UPDATE] Updating existing wallet settings for user {user_id[:8]}")
         settings = await update_user_wallet_settings(user_id, data)
 
     # Proactively create core user accounts when wallet is configured
     # This ensures all users have a consistent account structure from the start
+    logger.info(f"[WALLET UPDATE] Creating LIABILITY account for user {user_id[:8]}")
     await get_or_create_user_account(
         user_id, AccountType.LIABILITY, "Accounts Payable"
     )
+    logger.info(f"[WALLET UPDATE] Creating ASSET account for user {user_id[:8]}")
     await get_or_create_user_account(
         user_id, AccountType.ASSET, "Accounts Receivable"
     )
+    logger.info(f"[WALLET UPDATE] Completed update_user_wallet for user {user_id[:8]}")
 
     return settings