chore: restructure skills repo with new agents and skill bundles

- Add new skills: deep-dive, docs-rag, meta-creator, ppt-maker, sdlc
- Add agent configs: g-assistent, meta-creator, sdlc with prompt files
- Add reference docs for custom agents and skills specification
- Add utility scripts: install-agents.sh, orchestrate.py, puml2svg.sh
- Update README and commit-message skill config
- Remove deprecated skills: codereview, python, testing, typescript
- Add .gitignore

.gitignore

@@ -0,0 +1,22 @@
+# Python
+__pycache__/
+*.pyc
+*.pyo
+.venv/
+venv/
+
+# Node
+node_modules/
+npm-debug.log*
+
+# Eval outputs
+evals-workspace/
+*.eval-output.json
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Editor
+.vscode/
+*.swp