feat(api): Add bank logo support and fix banks endpoint type errors.

Backend changes:
- Add logo field to AccountDetails model
- Update accounts API endpoints to include logo data
- Add database migration for logo column in accounts table
- Implement institution details fetching from GoCardless API
- Enrich account data with institution logos during sync
- Fix type errors in banks endpoint with proper response parsing

Frontend changes:
- Add failedImages state to track logo loading failures
- Implement conditional rendering to show bank logos when available
- Add proper error handling with fallback to Building2 icon
- Fix image sizing to w-6 h-6 sm:w-8 sm:h-8 for proper display
- Update Account interface to include optional logo field
- Remove unused useState import from System component

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

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

leggen/api/routes/banks.py

@@ -21,18 +21,19 @@ async def get_bank_institutions(
 ) -> APIResponse:
     """Get available bank institutions for a country"""
     try:
-        institutions_data = await gocardless_service.get_institutions(country)
+        institutions_response = await gocardless_service.get_institutions(country)
+        institutions_data = institutions_response.get("results", [])
 
         institutions = [
             BankInstitution(
                 id=inst["id"],
                 name=inst["name"],
                 bic=inst.get("bic"),
-                transaction_total_days=inst["transaction_total_days"],
+                transaction_total_days=int(inst["transaction_total_days"]),
                 countries=inst["countries"],
                 logo=inst.get("logo"),
             )
-            for inst in institutions_data.get("results", [])
+            for inst in institutions_data
         ]
 
         return APIResponse(