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

skills/sdlc/assets/phase-checklist.md

@@ -0,0 +1,32 @@
+# Phase Quick-Reference Checklist
+
+## Phase 1 — Requirements
+- [ ] Problem statement written (1–3 sentences)
+- [ ] Functional requirements listed (FR-N format)
+- [ ] Non-functional requirements listed
+- [ ] Constraints documented
+- [ ] Out-of-scope items explicit
+- [ ] Open questions listed
+
+## Phase 2 — Design
+- [ ] Architecture style chosen with rationale
+- [ ] Component diagram (PlantUML)
+- [ ] Data model diagram (PlantUML)
+- [ ] External dependencies table
+- [ ] ADRs written (decision + rationale)
+- [ ] Risks table with mitigations
+
+## Phase 3 — Tasks
+- [ ] Work grouped into milestones
+- [ ] Each task: estimable, independent, linked to FR
+- [ ] Dependencies identified
+- [ ] Critical path flagged
+- [ ] Parallelizable tasks noted
+
+## Phase 4 — Implementation Plan
+- [ ] Setup checklist written
+- [ ] Tasks ordered by dependency + priority
+- [ ] Each task has acceptance criteria
+- [ ] Each task has implementation notes
+- [ ] Each task has Definition of Done
+- [ ] "Day 1" first task identified