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/ppt-maker/assets/architecture.puml

@@ -0,0 +1,30 @@
+@startuml ppt-maker-architecture
+skinparam componentStyle rectangle
+skinparam defaultFontName Arial
+skinparam backgroundColor #FAFAFA
+
+package "ppt-maker Skill" {
+  component "SKILL.md\n(instructions)" as SKILL
+  component "scripts/ppt-maker.js\n(core engine)" as ENGINE
+  component "scripts/package.json\n(deps: pptxgenjs)" as PKG
+}
+
+package "ppt-maker.js Internals" {
+  component "Markdown Parser\n(slides, headings, lists)" as PARSER
+  component "Chart Detector\n(keyword → pie/bar/line)" as CHART
+  component "Theme Engine\n(ocean/sunset/purple/...)" as THEME
+  component "PPTX Renderer\n(pptxgenjs)" as RENDERER
+}
+
+actor User
+
+User --> SKILL : natural language request
+SKILL --> ENGINE : node ppt-maker.js -i ... -o ... -t ...
+ENGINE --> PARSER
+ENGINE --> CHART
+ENGINE --> THEME
+PARSER --> RENDERER
+CHART --> RENDERER
+THEME --> RENDERER
+RENDERER --> User : output.pptx
+@enduml

skills/ppt-maker/assets/workflow.puml

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+@startuml ppt-maker-workflow
+skinparam defaultFontName Arial
+skinparam backgroundColor #FAFAFA
+
+actor User
+participant "ppt-maker\nSkill" as SKILL
+participant "ppt-maker.js" as ENGINE
+
+User -> SKILL : "生成一份PPT: <描述>"
+SKILL -> SKILL : generate Markdown content
+SKILL -> ENGINE : node ppt-maker.js -i input.md -o out.pptx -t <theme>
+
+ENGINE -> ENGINE : parse slides\n(# → cover, ## → content, ## 感谢 → end)
+
+loop each ## slide
+  ENGINE -> ENGINE : scan headings for chart keywords
+  alt chart keyword found & table present
+    ENGINE -> ENGINE : render pie / bar / line chart
+  else
+    ENGINE -> ENGINE : render text / list / table
+  end
+end
+
+ENGINE --> User : output.pptx
+@enduml