jp-sync: update AI skills and theming-mcp docs to match EN restructure

Sync jp/components/ai/skills.md and jp/components/ai/theming-mcp.md
with the updated English source files from the latest push.

Changes to jp/components/ai/skills.md:
- Update frontmatter: add _license: MIT, mentionedTypes: []; update
  title, description, and keywords to align with EN
- Translate new NOTE about evolving AI tooling landscape
- Replace Method 1/2 structure with ## スキルの場所 (Skill Locations)
  section covering GitHub Copilot, Claude, Cursor, Gemini CLI,
  Antigravity, Junie, and Windsurf per-tool tables
- Replace Method 2 with ## スキルのインストール (Installing Skills)
  using Options A (npm), B (gemini skills CLI), C (npx skills CLI),
  matching the EN Option A/B/C structure
- Update ## その他のリソース links to match EN

Changes to jp/components/ai/theming-mcp.md:
- Update frontmatter: add _license: MIT, mentionedTypes: []; update
  title and keywords to align with EN
- Update Prerequisites: remove specific version details, update install
  command from ng add to npm install igniteui-theming
- Fix detect_platform troubleshooting typo (package.jso -> package.json)
- Update Additional Resources to match EN (skills.md link + commented
  theming links)
- Fix Palettes link to use absolute URL matching EN

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

Author: github-actions[bot]