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>

frontend/src/types/api.ts

@@ -13,6 +13,7 @@ export interface Account {
   name?: string;
   display_name?: string;
   currency?: string;
+  logo?: string;
   created: string;
   last_accessed?: string;
   balances: AccountBalance[];