feat: add on-demand workflow_dispatch trigger to auto-triage-issues for label backfill

[Copilot]

There are currently unlabeled open issues that the scheduled every-6h triage pass handles incrementally, but with no way to trigger a full backfill on-demand.

Changes

• auto-triage-issues.md: Add explicit workflow_dispatch: to the on: block, enabling maintainers to trigger a backfill run directly from the GitHub Actions UI.
• New prompt section — "On Manual/On-Demand Runs (workflow_dispatch)": Instructs the agent to fetch all open unlabeled issues (no pre-filter cap), process up to 10 per run (safe-output limit), and emit a discussion report showing what was labeled and how many unlabeled issues remain for subsequent passes. Scheduled and issue-event behavior is unchanged.
• auto-triage-issues.lock.yml: Recompiled (frontmatter hash bump only).

on:
  issues:
    types: [opened, edited]
  schedule: every 6h
  workflow_dispatch:          # ← new: enables manual backfill from Actions UI

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[Copilot]

Pull request overview

Adds explicit support and guidance for running the auto-triage agent on-demand so maintainers can trigger an unlabeled-issue backfill via GitHub Actions.

Changes:

• Add workflow_dispatch to the workflow’s on: block in auto-triage-issues.md.
• Add a new “On Manual/On-Demand Runs (workflow_dispatch)” section describing manual backfill behavior and reporting.
• Recompile the generated lockfile (frontmatter hash bump).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
.github/workflows/auto-triage-issues.md	Adds the manual trigger and documents how manual backfill runs should fetch/process/report unlabeled issues.
.github/workflows/auto-triage-issues.lock.yml	Regenerated metadata hash for the compiled workflow.

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[Copilot]

The compiled workflow already contains a workflow_dispatch trigger (see .github/workflows/auto-triage-issues.lock.yml), so this change may not actually be what enables manual runs from the Actions UI. Consider either (a) updating the PR description to clarify that this mostly aligns the source .md with the already-generated workflow, or (b) confirming the generator won't inject workflow_dispatch by default and adjusting accordingly to avoid confusion about what behavior is changing.

[Copilot]

For manual backfill runs, instructing the agent to "fetch ALL open issues without any labels" is likely to require paginating potentially large result sets, which can exceed the workflow’s configured rate limit (5/min) and 15-minute timeout. A more reliable approach is to use a search/list call that returns a total count (or first page + total_count), then fetch only enough pages to process the next 10 issues while still reporting how many unlabeled issues remain.

Suggested change

	1. **Fetch ALL open issues without any labels** using GitHub tools — do not limit to a fixed count
	2. **Process up to 10 unlabeled issues** in this run (respecting safe-output limits); if more exist, note the remainder in the report
	1. **Determine the total number of open issues without any labels** using a GitHub search/list API that returns a `total_count` (or first page + `total_count`), without iterating through all pages
	2. **Fetch and process only the next batch of up to 10 unlabeled issues** in this run (respecting safe-output limits); if more exist, use the total count to note the remaining unlabeled issues in the report