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/javascript-intro/ScopeDemo.vue

@@ -1,5 +1,5 @@
 <script setup>
-import { ref } from 'vue'
+import { ref, watch } from 'vue'
 
 const activeScope = ref('global')
 const explanation = ref('')
@@ -65,7 +65,7 @@ updateExplanation()
       <!-- 作用域层级图 -->
       <div class="scope-levels">
         <div
-          v-for="(scope, index) in scopes"
+          v-for="scope in scopes"
           :key="scope.id"
           class="level"
           :class="{ active: activeScope === scope.id, dimmed: activeScope !== scope.id }"