**Title:** fix: publish all four bulk payment contract events to the ledger

[alfeedrips]

---

Body:

Summary

All four event types in contracts/bulk_payment/src/lib.rs were constructed as bare struct expressions and immediately dropped, so zero events were ever emitted to the Soroban ledger. This broke the backend contract event indexer (contractEventIndexer.ts) which depends on these events for real-time payment tracking and analytics, and violated on-chain auditability for bulk payments.

Changes

• contracts/bulk_payment/src/lib.rs — Added .publish(&env) to all four event construction sites:

  • BatchExecutedEvent in execute_batch (line 161)
  • PaymentSkippedEvent in execute_batch_partial loop (line 217)
  • PaymentSentEvent in execute_batch_partial loop (line 228)
  • BatchPartialEvent in execute_batch_partial (line 253)

• contracts/bulk_payment/src/test.rs — Added 2 new tests + helper:

  • has_event() helper that matches events by contract address and snake_case topic symbol via env.events().all() + Symbol::from_val
  • test_execute_batch_emits_batch_executed_event — verifies execute_batch publishes batch_executed_event
  • test_execute_batch_partial_emits_all_events — verifies execute_batch_partial publishes payment_sent_event, payment_skipped_event, and batch_partial_event when some payments succeed and others are skipped

Testing

cargo test -p bulk_payment

Result: 15/15 passing (13 existing + 2 new event emission tests)

Test	Status
test_execute_batch_emits_batch_executed_event	NEW - passes
test_execute_batch_partial_emits_all_events	NEW - passes
All 13 pre-existing tests	unchanged - pass

Tradeoffs

• Event topic format: The #[contractevent] macro generates snake_case topic symbols (e.g., batch_executed_event for BatchExecutedEvent). The tests match on this format. If the macro behavior changes in a future Soroban SDK version, the tests will catch it.
• No data field assertions: The tests verify event presence via topic matching but do not assert on the event data payload fields. This keeps tests resilient to serialization format changes while still confirming events are published. The snapshot files (test_snapshots/) capture the full event data for manual inspection if needed.

Architecture

The fix is minimal — each event struct already had the correct fields populated at the right call sites. The only change is appending .publish(&env) to convert the struct expression from a no-op into an actual Soroban event emission. The backend indexer (contractEventIndexer.ts) fetches all contract events from Soroban RPC generically, so no indexer-side changes are needed.

Out of scope

• Sibling contract cross_asset_payment has the identical bug (separate issue)
• Adding new event types or changing event field shapes
• Indexer-side changes

---

Closes #390