Customize daily-doc-updater workflow for copilot-sdk-clojure

- Switch engine from claude to copilot (default)
- Add Java 21, Clojure CLI, and Babashka setup steps
- Add dependency caching (mirrors ci.yml)
- Update bash tool permissions: broaden find/grep to full repo
- Add bb validate-docs and bb test to allowed commands
- Import .github/copilot-instructions.md at runtime
- Remove upstream gh-aw source tracking and mood import
- Rewrite agent instructions for Clojure SDK doc structure
- Reference correct doc/ paths, style guide, and validation

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: krukow