ci: add cascading notification support

[mateodelnorte]

Summary

• Adds repository_dispatch trigger to CI so upstream dependency updates run the test suite
• Adds notify-parent.yml to notify the meta parent repo after CI passes (on push or upstream cascade)

Test plan

• Verify CI still runs on push/PR
• After merge, verify notify-parent dispatches to meta

🤖 Generated with Claude Code

[coderabbitai]

Warning

Rate limit exceeded

@mateodelnorte has exceeded the limit for the number of commits that can be reviewed per hour. Please wait 5 minutes and 55 seconds before requesting another review.

⌛ How to resolve this issue?

After the wait time has elapsed, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

We recommend that you space out your commits to avoid hitting the rate limit.

🚦 How do rate limits work?

CodeRabbit enforces hourly rate limits for each developer per organization.

Our paid plans have higher rate limits than the trial, open-source and free plans. In all cases, we re-allow further reviews after a brief timeout.

Please see our FAQ for further information.

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch ci/cascading-notifications

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}