Add AI search query expansion

app/templates/search/index.html

@@ -20,7 +20,31 @@
     </form>
 </section>
 
+{% if query and ai_available %}
+<section class="card" style="margin-top: 8px;">
+    {% if ai_activated %}
+    <span class="muted">AI 搜索已启用</span>
+    {% else %}
+    <a href="/search?q={{ query | urlencode }}&ai=1" class="button button-secondary" style="display:inline-block; text-decoration:none;">
+        AI 智能搜索
+    </a>
+    {% endif %}
+</section>
+{% endif %}
+
 {% if searched %}
+    {% if ai_error %}
+    <section class="card" style="margin-top: 8px; border-color: #b42318;">
+        <p style="margin:0; color: #b42318;"><strong>{{ ai_error }}</strong></p>
+    </section>
+    {% endif %}
+
+    {% if ai_activated and expanded_terms %}
+    <section class="card" style="margin-top: 8px; border-color: #0b57d0;">
+        <p style="margin:0; color: #0b57d0;"><strong>AI 帮你扩展了：</strong>{{ expanded_terms | join('、') }}</p>
+    </section>
+    {% endif %}
+
     {% if results %}
     <section class="stack">
         <p class="muted">共找到 {{ results|length }} 条结果。</p>

app/templates/settings/form.html

@@ -47,6 +47,20 @@
         {% endif %}
     </label>
 
+    <hr style="border:none;border-top:1px solid #ddd;margin:16px 0;">
+
+    <label class="form-field checkbox-row">
+        <input type="checkbox" name="ai_search_enabled" {% if config.ai_search_enabled %}checked{% endif %}>
+        启用 AI 智能搜索
+    </label>
+    <p class="checkbox-help">开启后，搜索页将显示「AI 智能搜索」按钮，通过查询词扩展增强搜索结果。</p>
+
+    <label class="form-field">
+        额外领域提示（可选）
+        <textarea name="ai_search_extra_hints" rows="3" placeholder="例如：用户物品主要涉及厨房用品和电子产品">{% if config.ai_search_extra_hints %}{{ config.ai_search_extra_hints }}{% endif %}</textarea>
+    </label>
+    <p class="checkbox-help">追加到 AI 搜索提示词末尾，帮助模型理解你的物品领域。留空则使用默认提示词。</p>
+
     <div class="form-actions">
         <button type="submit" class="button button-primary">保存设置</button>
         <button type="submit" class="button button-secondary" formaction="/settings/test" formmethod="post">测试连接</button>