Add event-driven agent workflows

[Carson Radtke (carsonRadtke)]

Summary

• Add event-driven issue triage, root-cause analysis, and coding-agent handoff workflows.
• Add automated pull request classification, first-pass review, and human reviewer assignment.
• Add custom Copilot agents, deterministic label synchronization, and cloud-agent setup guidance.

Workflow

1. New or edited issues are classified by priority, kind, scope, and status.
2. Status: Triaged starts RCA and creates a draft PR containing a failing regression test.
3. Status: RCA Complete assigns the coding agent to the existing RCA PR.
4. New and updated PRs receive an automated non-approving review.
5. Reviewed non-draft PRs request review from @carsonradtke.

Security review

The PR review workflows intentionally use pull_request_target so fork PRs can be labeled and reviewed. Both set checkout: false; agents read fork diffs through GitHub API tools and cannot execute or edit fork code. GH_AW_AGENT_TOKEN is isolated from agent execution and is available only to restricted safe-output jobs.

Repository setup

Before enabling the workflows:

• Configure the GH_AW_AGENT_TOKEN Actions secret with the permissions documented in .github/AGENTIC_WORKFLOWS.md.
• Enable the relevant Copilot cloud-agent and Copilot CLI organization policies.

The label synchronization workflow creates or updates the required labels after merge without deleting existing labels.

Validation

• Compiled all five agentic workflows with gh aw compile --validate --approve.
• Previewed synchronization of all 55 labels.
• Performed two independent reviews of the complete local diff.