Improve feed handling for PR review request and thread events

[blindndangerous]

Summary

• Improve activity-feed handling for additional PR review-related events so they behave like existing PR feed items.
• Add clearer text for review-request lifecycle actions, including requested reviewer/team where available.
• Route more feed events into in-app dialogs instead of browser fallback when a native view exists.

What Changed

• Added explicit handling for PullRequestReviewThreadEvent in feed formatting and open behavior.

• Improved PullRequestEvent action strings for:

  • Review_requested

  • Review_request_removed

  • Ready_for_review

  • converted_to_draft

  • synchronize

• Updated feed open routing:

  • PR review thread events now open the PR dialog.
  • Commit comment events open the commits dialog.
  • Wiki/member events open the repo dialog.

• Included PR review thread events in feed PR-title backfill key extraction.

Testing Status

• Draft PR: human validation is still pending because there is not currently a reliable live test case for these event variants.
• Build was produced successfully from this branch for manual testing.

Stacked PR Notes

• Depends on Add PR review comments to pull request dialog #4 (which depends on Backfill missing PR and issue titles in activity feed #3 -> Add native discussion dialog support for feed and notifications #2 -> Improve activity feed text for issue/PR events #1).
• After lower stacked PRs merge, this PR should contain only this feed-event behavior delta.

Attribution

• Implemented by an AI agent: OpenAI Codex (GPT-5).
• Pending additional human validation via application build.