feat: 文章标签展示、搜索框清除按钮

- 文章详情页和文章卡片展示标签
- 搜索框右侧添加 × 清除按钮
- 标签点击跳转文章列表页自动搜索
- 修复 hasAnyFilter 未包含 tags 的 bug

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/blog/PostCard.vue

@@ -86,6 +86,16 @@ function renderDesc(): string {
               v-html="renderDesc()"
             />
 
+            <div v-if="post.tags?.length" class="mt-2 flex flex-wrap gap-1.5">
+              <span
+                v-for="tag in post.tags"
+                :key="tag"
+                class="tag-pill"
+              >
+                {{ tag }}
+              </span>
+            </div>
+
             <div v-if="matchedLines && matchedLines.length > 0" class="mt-3 space-y-1.5">
               <div
                 v-for="(line, idx) in (expanded ? matchedLines : matchedLines.slice(0, 3))"