[DOCS] Migrate documentation from VuePress 1.x to VitePress (#2299)

- Replace VuePress 1.9.10 with VitePress 1.6.4
- Convert config from CommonJS to ESM TypeScript (config.mts)
- Convert shared Theengs nav config to ESM (commonConfig.mts)
- Rewrite BoardEnvironmentTable in Vue 3 Composition API
- Rewrite FlashEnvironmentSelector in Vue 3 Composition API
- Enable built-in local search and dark mode
- Add medium-zoom for image zoom
- Use VitePress CSS variables for dark mode compatibility
- Update CI script paths from .vuepress to .vitepress
- Update .gitignore for VitePress build artifacts
- Rename README.md files to index.md (VitePress convention)
- Fix markdown compatibility (angle-bracket escaping, image paths)
- Drop PWA plugin (not needed)

Co-authored-by: Florian <1technophile@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -24,11 +24,11 @@ managed_components
 .github/*instructions.md
 .github/workflows/_docs
 # CI/CD Generated outputs
-docs/.vuepress/dist/
-docs/.vuepress/public/boards-info.json
-docs/.vuepress/public/commonConfig.js 
-docs/.vuepress/public/firmware_build
-
+docs/.vitepress/dist/
+docs/.vitepress/cache/
+docs/.vitepress/public/boards-info.json
+docs/.vitepress/public/commonConfig.js
+docs/.vitepress/public/firmware_build
 
 # Generated site/firmware/reports files
 generated/
@@ -41,8 +41,10 @@ scripts/latest_version.json
 scripts/latest_version_dev.json
 
 # Generated configuration files
-docs/.vuepress/meta.json
+docs/.vitepress/meta.json
 
 # Generated full documentation pages
 docs/prerequisites/board-full.md
 docs/upload/web-install-full.md
+.superpowers/
+docs/superpowers/