ci: add issue-implementer workflow with dispatch chaining #27
Description
Add an issue-implementer agentic workflow that code-health and test-audit agents dispatch after creating issues.
- Issue-implementer reads the issue spec, implements the solution with Claude Opus 4.6, and opens a PR
- Code-health and test-audit agents use dispatch-workflow to trigger it with the issue number
- Issue titles prefixed with [aw][code health] or [aw][test audit] and labeled accordingly