Auto-triage: label-gated follow-up, partial-progress acknowledgement, and /triage on-demand command (#4324)

* Add one-time follow-up triage when author provides missing env info

Extends the issue auto-triage workflow so a second (and final) triage
summary is produced when:
  1. The first triage flagged missing environment fields, AND
  2. The original issue author responds with a follow-up comment.

No further triage runs after the second summary. Comments from other
users, bots, or on PRs do not trigger re-triage.

NOTE: Maintainers must run 'gh aw compile' to regenerate
.github/workflows/issue-triage.lock.yml from this .md source.

* Regenerate issue-triage.lock.yml (gh aw compile v0.72.1)

* Add label gate, /triage on-demand, and partial-progress follow-up routing

* Silence noop tracking issue (report-as-issue: false)

* Exclude /triage prefix from author follow-up branch

Prevents non-maintainer issue authors from invoking the on-demand /triage command via the author+label follow-up branch. Lock file regenerated with gh aw compile v0.72.1.

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

* Tighten /triage command matching to strict token

Replace startsWith(body, '/triage') with strict token match (body == '/triage' || startsWith(body, '/triage ')) in both maintainer and author branches of the workflow-level if: gate so /triage-foo, /triagery, etc. no longer falsely match. Lock file regenerated with gh aw compile v0.72.1.

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Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: priyankatiwari08