test: add NIP-40 standalone expiration integration coverage

[Priyanshubhartistm]

Description

• Added NIP-40 standalone Gherkin scenarios in test/integration/features/nip-40/nip-40.feature.
• Added step definitions in test/integration/features/nip-40/nip-40.feature.ts.
• Scenario coverage added exactly as requested:
  • Kind 1 event with past expiration is not returned via REQ.
  • Kind 1 event with future expiration is returned via REQ.
  • Kind 1 event that expires after storage is not served to new subscribers.
• Step definitions use EventTags.Expiration and EventExpirationTimeMetadataKey from src/constants/base.ts.
• Added minimal test helper support in test/integration/features/helpers.ts to publish events without forcing expected OK success, so expiration edge cases can be asserted cleanly.
• Scope is test-only for this PR.

Related Issue

• test: integration tests for NIP-40 event expiration (standalone events) #502

Motivation and Context

• NIP-33 already validates expiration behavior for parameterized replaceable events.
• There was no integration coverage for ordinary standalone events like kind 1 text notes.
• This closes that gap and codifies expected relay behavior for NIP-40 on non-replaceable events.

How Has This Been Tested?

• Local pre-commit hook pipeline executed successfully:
  • lint
  • build:check
  • unit tests
• Integration suite command run:
  • npm run docker:test:integration -- test/integration/features/nip-40/nip-40.feature
• Observed behavior:
  • Scenario 1 passed.
  • Scenario 2 passed.
  • Scenario 3 currently fails against existing relay implementation, which is expected for a test-only PR that captures issue behavior.

Screenshots (if appropriate):

• N/A

Types of changes

• Non-functional change (docs, style, minor refactor)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my code changes.
• I added a changeset, or this is docs-only and I added an empty changeset.
• All new and existing tests passed.

[coveralls]

coverage: 74.483% (+0.1%) from 74.365% — Priyanshubhartistm:test/nip-40-event-expiration into cameri:main

[Copilot]

Pull request overview

Adds standalone (kind 1 / text_note) NIP-40 expiration integration coverage to complement existing NIP-33 expiration tests, plus a small integration-test helper refactor to allow asserting rejected publishes.

Changes:

• Added Gherkin scenarios for expired-in-past, expires-in-future, and post-storage-expiration behavior for kind 1 events.
• Added Cucumber step definitions for publishing expiring text_note events, waiting for expiration, subscribing, and asserting EOSE + counts.
• Added a lower-level publishEvent helper to observe OK results without forcing expected success, and reimplemented sendEvent on top.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
test/integration/features/nip-40/nip-40.feature	Adds NIP-40 standalone expiration scenarios for kind 1 events.
test/integration/features/nip-40/nip-40.feature.ts	Implements the step definitions to publish expiring events and assert subscription results.
test/integration/features/helpers.ts	Introduces publishEvent and refactors sendEvent to allow asserting unsuccessful publishes.
.changeset/empty-nip40-tests.md	Adds an “empty” changeset note for the test-only change.

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[Priyanshubhartistm]

Hey @cameri, I resolved the merge conflicts and pushed the updated branch.
Please take another look when you have a moment.
thanku