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/docs-rag/assets/architecture.puml

@@ -0,0 +1,24 @@
+@startuml docs-rag-architecture
+skinparam componentStyle rectangle
+skinparam defaultFontName Arial
+skinparam backgroundColor #FAFAFA
+
+package "docs-rag Skill" {
+  component "SKILL.md\n(instructions)" as SKILL
+  component "data/index.json\n(spec, title, keywords,\nsummary, file path)" as INDEX
+  component "evals/evals.json" as EVALS
+}
+
+package "Source Documents" {
+  database "docs/\n*.docx / *.doc\n(3GPP specs)" as DOCS
+  component "scripts/build_index.py\n(index builder)" as BUILDER
+}
+
+actor Developer
+
+Developer --> SKILL : 3GPP question
+SKILL --> INDEX : keyword + semantic match
+INDEX --> DOCS : read file (deep detail)
+BUILDER --> INDEX : builds / updates
+DOCS --> BUILDER : scans
+@enduml