feat(reusable-auto-resolve-conflicts): add stale release-please PR detection

[laurigates]

Summary

The claude-plugins repo's auto-resolve-conflicts.yml has custom logic to detect and close stale release-please--branches--* PRs that the reusable version lacks. This prevents migrating to the reusable workflow.

Missing feature

When checking for conflicting PRs, also detect stale release-please PRs (pattern: release-please--branches--*) and close them instead of attempting conflict resolution, since release-please will recreate them automatically.

Context

This logic exists in the local claude-plugins workflow and should be added as an optional behavior (e.g., close_stale_release_please: true input) in the reusable version.

[laurigates]

This is already implemented in reusable-auto-resolve-conflicts.yml. The release-please--branches--* pattern is handled unconditionally in the stale PR detection case statement (alongside dependabot/*, renovate/*, and chore/update-version-tracking-*). No optional input is needed — closing stale release-please PRs is always the correct behavior since release-please will recreate them automatically.