Adds super user balance overview

Implements functionality for super users to view a breakdown of outstanding balances for all users.

This includes:
- Adding an API endpoint to fetch all user balances.
- Updating the frontend to display these balances in a table, accessible only to super users.
- Modifying the balance calculation for the current user to reflect the total owed by or to the castle for super users.

This provides super users with a comprehensive view of the castle's financial position.

views_api.py

@@ -19,6 +19,7 @@ from .crud import (
     get_account_transactions,
     get_all_accounts,
     get_all_journal_entries,
+    get_all_user_balances,
     get_journal_entries_by_user,
     get_journal_entry,
     get_or_create_user_account,
@@ -382,7 +383,19 @@ async def api_get_my_balance(
     wallet: WalletTypeInfo = Depends(require_invoice_key),
 ) -> UserBalance:
     """Get current user's balance with the Castle"""
-    return await get_user_balance(wallet.wallet.id)
+    from lnbits.settings import settings as lnbits_settings
+
+    # If super user, show total castle liabilities (what castle owes to all users)
+    if wallet.wallet.user == lnbits_settings.super_user:
+        all_balances = await get_all_user_balances()
+        total_owed = sum(b.balance for b in all_balances if b.balance > 0)
+        # Return as castle's "balance" - positive means castle owes money
+        return UserBalance(
+            user_id=wallet.wallet.user, balance=total_owed, accounts=[]
+        )
+
+    # For regular users, show their individual balance
+    return await get_user_balance(wallet.wallet.user)
 
 
 @castle_api_router.get("/api/v1/balance/{user_id}")
@@ -391,6 +404,14 @@ async def api_get_user_balance(user_id: str) -> UserBalance:
     return await get_user_balance(user_id)
 
 
+@castle_api_router.get("/api/v1/balances/all")
+async def api_get_all_balances(
+    wallet: WalletTypeInfo = Depends(require_admin_key),
+) -> list[UserBalance]:
+    """Get all user balances (admin/super user only)"""
+    return await get_all_user_balances()
+
+
 # ===== PAYMENT ENDPOINTS =====