Create script that flags PRs for triage, the same way as for a2ui.

[polina-c]

What

Adds an automation that flags stale, externally-authored pull requests with the status: needs-triage label, mirroring the triage setup used in the a2ui repo.

Why

Makes PRs that need maintainer attention easy to find. The label is fully owned by the automation and reconciled on every run — added to PRs that match the rule and removed once they no longer do.

Rule

A PR is flagged when it is opened by an external contributor (maintainers manage their own PRs) and is stale: no internal member has responded for more than 1 day after the author's last contribution. Staleness is measured from the last human contribution — a comment, review, inline review comment, or the opening post if there are none — rather than updated_at, so the bot's own label edits never reset the clock.

Changes

• tool/triage.mjs (new) — the reconciliation logic. Gathers each PR's contributions from three endpoints (issue comments, formal reviews, inline review comments) so a maintainer responding via a review or inline comment counts as an answer. Fetches in bounded concurrent batches, falls back gracefully on per-source errors, and re-reads live labels before mutating to avoid double-labeling from overlapping runs.
• .github/workflows/triage.yaml (new) — runs the script daily (15:00 UTC) and on the PR events that can change flag state (pull_request_target, issue_comment, pull_request_review, pull_request_review_comment), plus manual dispatch.
• CONTRIBUTING.md — note that issues are filed against the A2UI project with the component: genui label.

[gemini-code-assist]

Code Review

This pull request updates the issue filing instructions in CONTRIBUTING.md and introduces a new PR triage script (scripts/triage.mjs) to automate the reconciliation of the 'status: needs-triage' label. Feedback on the triage script highlights a high-severity issue where PR reviews and inline comments are missed, potentially causing false positives. Additionally, suggestions were made to handle deleted users correctly in the bot check and to optimize the retrieval of the last human contribution using Array.prototype.find() since comments are fetched in descending order.

[github-actions]

Package publishing

If you have publishing permissions, you can use the links below to publish the changes after merging this PR.

Package	Version	Status	Publish tag (post-merge)
package:a2ui_core	0.0.1-wip002	ready to publish	a2ui_core-v0.0.1-wip002
package:genai_primitives	0.2.4	ready to publish	genai_primitives-v0.2.4
package:genui	0.9.2	(error) pubspec version (0.9.2) and changelog (0.10.0) don't agree
package:genui_a2a	0.9.0	(error) pubspec version (0.9.0) and changelog (0.10.0) don't agree
package:json_schema_builder	0.1.5	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.