feat: Pluggable bank connector architecture

[flaggdavid-source]

Summary

Implements a pluggable architecture for bank integrations as requested in issue #75.

Changes

New Files

1. app/services/bank_connectors/__init__.py - Module entry point

2. app/services/bank_connectors/base.py - Abstract base class BankConnector defining the interface:

   • connector_type / display_name properties
   • connect() / disconnect() methods
   • import_transactions(from_date, to_date) - Import transactions within date range
   • refresh_transactions(from_date) - Get new transactions since last sync
   • get_account_balance() - Get current balance
   • validate_credentials() - Validate credentials

3. app/services/bank_connectors/registry.py - Registry for managing connectors

4. app/services/bank_connectors/mock.py - Mock connector for testing/development

5. app/routes/bank_connectors.py - REST API endpoints:

   • GET /bank-connectors/types - List available connector types
   • GET /bank-connectors - List user's connectors
   • POST /bank-connectors - Create a connector
   • POST /bank-connectors/<id>/import - Import transactions
   • POST /bank-connectors/<id>/refresh - Refresh transactions
   • GET /bank-connectors/<id>/balance - Get account balance

6. tests/test_bank_connectors.py - 16 unit tests (all passing)

Modified Files

• app/db/schema.sql - Added bank_connectors table
• app/models.py - Added BankConnector model
• app/routes/__init__.py - Registered bank_connectors blueprint

Acceptance Criteria Met

✅ Connector interface - Abstract base class with all required methods
✅ Import & refresh support - Both methods implemented with date filtering
✅ Mock connector included - Full mock implementation for testing

Testing

All 16 tests pass:

tests/test_bank_connectors.py::TestConnectorRegistry - 3 passed
tests/test_bank_connectors.py::TestMockConnector - 10 passed  
tests/test_bank_connectors.py::TestTransactionModel - 1 passed
tests/test_bank_connectors.py::TestConnectorConfig - 2 passed