[seanthimons]

Summary

• Release the Shiny app at the same version and tag as singlehit, syncing its package metadata and checking the sync before publication.
• Group app changes under a “Shiny app” section in generated release notes.
• Document app installation, release pairing, and usage; add tests for release syncing and notes filtering.

Testing

• Full root test suite: 511 passed, 0 failed, 6 skipped.
• Formatter check initially reported files needing formatting; formatting was applied.