feat: 添加网络搜索功能（Tavily Search）

- 后端：新增 search_config 表存储搜索接口配置
- 后端：实现 /api/search 和 /api/search/detail API
- 前端：首页添加搜索配置入口（模态框）
- 前端：主题详情页添加搜索面板（搜索框+结果列表+详情查看）
- 搜索结果可一键添加为素材
- 支持搜索深度和时间范围筛选
- 更新 README 文档

app.py

@@ -117,6 +117,12 @@ def init_db():
             FOREIGN KEY (topic_id) REFERENCES topics(id) ON DELETE CASCADE,
             FOREIGN KEY (tag_id) REFERENCES tags(id) ON DELETE CASCADE
         );
+        CREATE TABLE IF NOT EXISTS search_config (
+            id INTEGER PRIMARY KEY CHECK (id = 1),
+            provider TEXT DEFAULT 'tavily',
+            api_key TEXT DEFAULT '',
+            updated_at TEXT DEFAULT (datetime('now','localtime'))
+        );
     ''')
     # 初始化默认Prompt模板
     default_templates = [
@@ -147,6 +153,9 @@ def init_db():
         conn.execute('ALTER TABLE materials ADD COLUMN selected INTEGER DEFAULT 1')
     except Exception:
         pass
+    # 初始化默认搜索配置
+    conn.execute('INSERT OR IGNORE INTO search_config (id, provider, api_key) VALUES (1, ?, ?)',
+                 ('tavily', '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'))
     conn.close()
 
 
@@ -724,6 +733,133 @@ def analyze_material(material_id):
     return jsonify({'analysis': analysis_text})
 
 
+# ==================== 搜索配置与搜索API ====================
+
+def get_search_config():
+    """从数据库读取搜索配置"""
+    conn = get_db()
+    row = conn.execute('SELECT * FROM search_config WHERE id=1').fetchone()
+    conn.close()
+    if row and row['api_key']:
+        return {'provider': row['provider'], 'api_key': row['api_key']}
+    return {'provider': 'tavily', 'api_key': ''}
+
+
+@app.route('/api/search-config', methods=['GET'])
+def get_search_config_api():
+    config = get_search_config()
+    key = config['api_key']
+    masked = key[:8] + '***' + key[-4:] if len(key) > 12 else ('***' if key else '')
+    return jsonify({
+        'provider': config['provider'],
+        'api_key_masked': masked,
+        'api_key_set': bool(key)
+    })
+
+
+@app.route('/api/search-config', methods=['PUT'])
+def update_search_config():
+    data = request.get_json(force=True)
+    conn = get_db()
+    now = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+    current = conn.execute('SELECT * FROM search_config WHERE id=1').fetchone()
+    provider = data.get('provider', current['provider'] if current else 'tavily')
+    api_key = data.get('api_key', '') or (current['api_key'] if current else '')
+    conn.execute('''
+        INSERT INTO search_config (id, provider, api_key, updated_at) VALUES (1, ?, ?, ?)
+        ON CONFLICT(id) DO UPDATE SET provider=excluded.provider, api_key=excluded.api_key, updated_at=excluded.updated_at
+    ''', (provider, api_key, now))
+    conn.commit()
+    conn.close()
+    return jsonify({'ok': True})
+
+
+@app.route('/api/search', methods=['POST'])
+def search_web():
+    """调用 Tavily Search API 进行搜索"""
+    data = request.get_json(force=True)
+    query = data.get('query', '').strip()
+    if not query:
+        return jsonify({'error': '搜索关键词不能为空'}), 400
+
+    search_config = get_search_config()
+    if not search_config['api_key']:
+        return jsonify({'error': '请先配置搜索API Key（首页右上角设置）'}), 400
+
+    max_results = data.get('max_results', 8)
+    search_depth = data.get('search_depth', 'basic')
+    time_range = data.get('time_range', None)
+
+    try:
+        req_body = {
+            'query': query,
+            'max_results': max_results,
+            'search_depth': search_depth,
+            'include_raw_content': False,
+        }
+        if time_range:
+            req_body['time_range'] = time_range
+
+        resp = requests.post(
+            'https://api.tavily.com/search',
+            headers={
+                'Authorization': f"Bearer {search_config['api_key']}",
+                'Content-Type': 'application/json'
+            },
+            json=req_body,
+            timeout=30
+        )
+        resp.raise_for_status()
+        result = resp.json()
+        return jsonify(result)
+    except requests.exceptions.HTTPError as e:
+        return jsonify({'error': f'搜索请求失败: HTTP {e.response.status_code}'}), 502
+    except Exception as e:
+        return jsonify({'error': f'搜索失败: {str(e)}'}), 500
+
+
+@app.route('/api/search/detail', methods=['POST'])
+def search_detail():
+    """调用 Tavily Search API 获取详细内容（include_raw_content）"""
+    data = request.get_json(force=True)
+    query = data.get('query', '').strip()
+    url = data.get('url', '').strip()
+    if not query:
+        return jsonify({'error': '搜索关键词不能为空'}), 400
+
+    search_config = get_search_config()
+    if not search_config['api_key']:
+        return jsonify({'error': '请先配置搜索API Key'}), 400
+
+    try:
+        req_body = {
+            'query': query,
+            'max_results': 3,
+            'search_depth': 'advanced',
+            'include_raw_content': True,
+        }
+        if url:
+            req_body['include_domains'] = [url.split('/')[2]] if '/' in url else [url]
+
+        resp = requests.post(
+            'https://api.tavily.com/search',
+            headers={
+                'Authorization': f"Bearer {search_config['api_key']}",
+                'Content-Type': 'application/json'
+            },
+            json=req_body,
+            timeout=45
+        )
+        resp.raise_for_status()
+        result = resp.json()
+        # 如果指定了URL，过滤只返回该URL的结果
+        if url:
+            result['results'] = [r for r in result.get('results', []) if r.get('url') == url]
+        return jsonify(result)
+    except Exception as e:
+        return jsonify({'error': f'获取详情失败: {str(e)}'}), 500
+
+
 # ==================== LLM配置API ====================
 
 @app.route('/api/llm-config', methods=['GET'])