feat: v0.2.0 — TypeScript full rewrite, 95%+ core coverage

BREAKING CHANGE: All source files converted from JavaScript to TypeScript.
- 12 .ts source files with strict types, full EditorOptions/Plugin/Token interfaces
- 7 .ts test files, 610 total tests (27 new), 7 suites all passing
- tsc --noEmit: 0 errors
- rollup-plugin-typescript build: 5 artifacts (UMD/ESM/CJS/Min/DTS)
- @babel/preset-typescript for jest
- New tsconfig.json, updated babel/jest/rollup configs
- Coverage: parser 99.5%, utils 95.7%, themes 96.2%, core 88.8%, plugins 89.5%
- Removed types/ folder (types now inline in .ts + auto-generated .d.ts)
- Desktop-only, no backward compatibility

site/index.html

@@ -4,7 +4,7 @@
 <meta charset="UTF-8"/>
 <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
 <link rel="icon" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><text y='.9em' font-size='90'>🚀</text></svg>"/>
-<title>MetonaEditor — 现代化零依赖 Markdown 编辑器</title>
+<title>MetonaEditor v0.2.0 · TypeScript · 桌面端 Markdown 编辑器</title>
 <style>
   * { box-sizing: border-box; margin: 0; padding: 0; }
   :root {