Adds a GitHub Actions workflow that runs on PRs targeting `release/*`
branches to flag non-bug-fix cherry-picks.
## What it does
- Triggers on `pull_request_target` (opened, reopened, edited) for
`release/*` branches
- Checks if the PR title starts with `fix:` or `fix(scope):`
(conventional commit format)
- If not a bug fix, comments on the PR informing the author and emits a
warning (via `core.warning`), but does **not** fail the check
- Deduplicates comments on title edits by updating an existing comment
(identified by a hidden HTML marker) instead of creating a new one
> [!NOTE]
> Generated by Coder Agents