- Add supply_chain.go with VerifyManifestIntegrity (SHA256 content check)
- Add pinned-ref enforcement to GithubResolver.Fetch (rejects bare org/repo)
- Fix duplicate TestSlackAdapter_Type across channels_test.go and slack_test.go
- Fix sync.Once lock copy in audit_test.go resetAuditKeyCache
- Fix slack_test.go horizontal rule expectations to match implementation
- Existing tests updated with PLUGIN_ALLOW_UNPINNED=true for bare-ref specs
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>