fix: resolve all ESLint errors in Vue components

Fixed 22 ESLint errors across 26 Vue component files:
- Removed TypeScript type annotations from ReadingProgress.vue (converted to JS)
- Removed unused variables, imports, and duplicate function declarations
- Fixed HTML parsing errors (invalid attribute names, unclosed tags)
- Added missing :key directives to v-for loops
- Fixed duplicate object keys (backgroundImage)
- Replaced special characters in comments to avoid parsing issues
- Fixed malformed HTML tags (v-else", 003e attributes)

All warnings were left unchanged as requested. Build now passes with 0 errors.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/.vitepress/theme/components/appendix/frontend-engineering/BundlerComparisonDemo.vue

@@ -67,7 +67,7 @@
           <!-- 数据区域 -->
           <g class="data-areas">
             <polygon
-              v-for="(tool, toolIndex) in bundlers"
+              v-for="tool in bundlers"
               :key="tool.id"
               :points="getDataPoints(tool.scores)"
               :fill="tool.color"