Fix inverted transaction type logic in createTransaction

[kevintang513]

Summary

• Fixed inverted logic in createTransaction() that was causing payments to behave as requests and vice versa
• Changed condition from if (isRequestTransaction(transaction)) to if (!isRequestTransaction(transaction))
• All unit tests now pass (44 tests passing)

Changes

File: backend/database.ts:549

• Negated the isRequestTransaction() condition to correctly execute payment logic for payments
• Before: Request transactions were immediately completing with balance transfers (payment behavior)
• After: Payment transactions immediately complete with balance transfers; requests stay pending until accepted

Impact

This fixes a critical bug where:

• Payments were only sending notifications instead of transferring money and completing
• Requests were immediately transferring money and completing instead of waiting for acceptance

The logic now correctly implements:

• Payments: Debit sender → Credit receiver → Mark complete → Send "received" notification
• Requests: Send "requested" notification → Wait for acceptance

Test Plan

1. Run unit tests: yarn test:unit
   • All 44 tests should pass
   • Specifically, transactions.test.ts tests "should create a payment" and "should create a request" now pass
2. Manual testing:
   • Create a payment transaction and verify it immediately completes with balance transfer
   • Create a request transaction and verify it stays pending until accepted

🤖 Generated with Claude Code

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