🎯 重构登录逻辑：以人为核心的三种出战模式

核心变更:
- 单枪匹马 (solo) - 人类单独出战
- 组队团战 (team) - 人类 +N 龙虾
- 独当一面 (agent_only) - 龙虾单独出征

后端:
- users/views.py: 支持多选 agent_ids
- 新增 mode_names 映射
- 错误提示优化

前端:
- 新模式选择 UI（带图标和说明）
- 多选龙虾复选框
- 实时显示已选龙虾数量
- 选中模式高亮显示

测试:
- test_new_login.py: 完整测试三种模式
- 绑定第二只龙虾（龙虾监控 🦞）

结果:
✅ 单枪匹马 - 1 个人类座位
✅ 组队团战 - 1+N 个座位（人类 + 龙虾）
✅ 独当一面 - N 个龙虾座位

frontend/src/App.js

@@ -14,9 +14,9 @@ axios.interceptors.request.use(config => {
 function LoginPage() {
   const [username, setUsername] = useState('test');
   const [password, setPassword] = useState('test123');
-  const [loginMode, setLoginMode] = useState('human_only');
+  const [mode, setMode] = useState('solo');
   const [agents, setAgents] = useState([]);
-  const [selectedAgent, setSelectedAgent] = useState('');
+  const [selectedAgents, setSelectedAgents] = useState([]);
   const navigate = useNavigate();
 
   // 扫描本机龙虾
@@ -28,9 +28,6 @@ function LoginPage() {
     try {
       const res = await axios.get(`${API_BASE}/user/scan-local-agents/`);
       setAgents(res.data.agents || []);
-      if (res.data.agents?.length > 0) {
-        setSelectedAgent(res.data.agents[0].agent_id);
-      }
     } catch (error) {
       console.error('扫描龙虾失败:', error);
     }
@@ -42,24 +39,32 @@ function LoginPage() {
       const payload = {
         username,
         password,
-        login_mode: loginMode
+        mode
       };
       
-      if (loginMode !== 'human_only' && selectedAgent) {
-        payload.selected_agent_id = selectedAgent;
+      if (mode !== 'solo' && selectedAgents.length > 0) {
+        payload.agent_ids = selectedAgents;
       }
       
       const res = await axios.post(`${API_BASE}/auth/login/`, payload);
       localStorage.setItem('token', res.data.token);
       localStorage.setItem('user', JSON.stringify(res.data.user));
       localStorage.setItem('sessions', JSON.stringify(res.data.sessions));
-      localStorage.setItem('login_mode', res.data.login_mode);
+      localStorage.setItem('mode', res.data.mode);
       navigate('/meetings');
     } catch (error) {
       alert('登录失败：' + (error.response?.data?.detail || error.response?.data?.error || error.message));
     }
   };
 
+  const toggleAgent = (agentId) => {
+    setSelectedAgents(prev => 
+      prev.includes(agentId) 
+        ? prev.filter(id => id !== agentId)
+        : [...prev, agentId]
+    );
+  };
+
   return (
     <div style={styles.center}>
       <div style={styles.card}>
@@ -68,64 +73,71 @@ function LoginPage() {
           <input type="text" placeholder="用户名" value={username} onChange={e => setUsername(e.target.value)} style={styles.input} required />
           <input type="password" placeholder="密码" value={password} onChange={e => setPassword(e.target.value)} style={styles.input} required />
           
-          {/* 身份模式选择 */}
+          {/* 出战模式选择 */}
           <div style={{margin: '15px 0'}}>
-            <label style={{display: 'block', marginBottom: '10px', fontWeight: '600'}}>登录身份：</label>
-            <label style={{display: 'block', marginBottom: '8px', cursor: 'pointer'}}>
+            <label style={{display: 'block', marginBottom: '10px', fontWeight: '600'}}>🎯 出战模式：</label>
+            <label style={{display: 'block', marginBottom: '12px', cursor: 'pointer', padding: '10px', background: mode === 'solo' ? '#e7f3ff' : 'white', borderRadius: '8px', border: '1px solid #2196f3'}}>
               <input 
                 type="radio" 
-                name="loginMode" 
-                value="human_only" 
-                checked={loginMode === 'human_only'} 
-                onChange={e => setLoginMode(e.target.value)} 
+                name="mode" 
+                value="solo" 
+                checked={mode === 'solo'} 
+                onChange={e => setMode(e.target.value)} 
               />
-              {' '}👤 人类身份（纯人类参会）
+              {' '}🥷 <strong>单枪匹马</strong>（人类单独出战，不带龙虾）
             </label>
-            <label style={{display: 'block', marginBottom: '8px', cursor: 'pointer'}}>
+            <label style={{display: 'block', marginBottom: '12px', cursor: 'pointer', padding: '10px', background: mode === 'team' ? '#e7f3ff' : 'white', borderRadius: '8px', border: '1px solid #2196f3'}}>
               <input 
                 type="radio" 
-                name="loginMode" 
+                name="mode" 
+                value="team" 
+                checked={mode === 'team'} 
+                onChange={e => setMode(e.target.value)} 
+              />
+              {' '}🛡️ <strong>组队团战</strong>（人类 + N 只龙虾一起出战）
+            </label>
+            <label style={{display: 'block', marginBottom: '12px', cursor: 'pointer', padding: '10px', background: mode === 'agent_only' ? '#e7f3ff' : 'white', borderRadius: '8px', border: '1px solid #2196f3'}}>
+              <input 
+                type="radio" 
+                name="mode" 
                 value="agent_only" 
-                checked={loginMode === 'agent_only'} 
-                onChange={e => setLoginMode(e.target.value)} 
+                checked={mode === 'agent_only'} 
+                onChange={e => setMode(e.target.value)} 
               />
-              {' '}🦞 龙虾身份（Agent 参会）
-            </label>
-            <label style={{display: 'block', marginBottom: '8px', cursor: 'pointer'}}>
-              <input 
-                type="radio" 
-                name="loginMode" 
-                value="both" 
-                checked={loginMode === 'both'} 
-                onChange={e => setLoginMode(e.target.value)} 
-              />
-              {' '}👤+ 双重身份（人类 + 龙虾）
+              {' '}⚔️ <strong>独当一面</strong>（龙虾单独出征，人类不上场）
             </label>
           </div>
           
-          {/* 龙虾选择 */}
-          {loginMode !== 'human_only' && (
-            <div style={{margin: '15px 0'}}>
-              <label style={{display: 'block', marginBottom: '8px', fontWeight: '600'}}>选择龙虾：</label>
-              <select 
-                value={selectedAgent} 
-                onChange={e => setSelectedAgent(e.target.value)}
-                style={styles.input}
-              >
-                {agents.length === 0 ? (
-                  <option value="">未找到龙虾</option>
-                ) : (
-                  agents.map(a => (
-                    <option key={a.agent_id} value={a.agent_id}>
-                      {a.agent_id} ({a.instance_name})
-                    </option>
-                  ))
-                )}
-              </select>
+          {/* 龙虾选择（组队或独当一面） */}
+          {mode !== 'solo' && (
+            <div style={{margin: '15px 0', padding: '15px', background: '#f9f9f9', borderRadius: '8px'}}>
+              <label style={{display: 'block', marginBottom: '10px', fontWeight: '600'}}>🦐 选择龙虾队友：</label>
+              {agents.length === 0 ? (
+                <p style={{color: '#999', fontSize: '14px'}}>未找到可用龙虾</p>
+              ) : (
+                agents.map(a => (
+                  <label key={a.agent_id} style={{display: 'flex', alignItems: 'center', marginBottom: '8px', cursor: 'pointer'}}>
+                    <input 
+                      type="checkbox" 
+                      checked={selectedAgents.includes(a.agent_id)}
+                      onChange={() => toggleAgent(a.agent_id)}
+                      style={{marginRight: '10px'}}
+                    />
+                    <span style={{fontSize: '16px', marginRight: '8px'}}>{a.agent_emoji || '🤖'}</span>
+                    <span>{a.agent_id}</span>
+                    <span style={{color: '#999', fontSize: '12px', marginLeft: '8px'}}>({a.instance_name})</span>
+                  </label>
+                ))
+              )}
+              {selectedAgents.length > 0 && (
+                <p style={{marginTop: '10px', color: '#2196f3', fontWeight: '600'}}>
+                  已选 {selectedAgents.length} 只龙虾队友 🦸
+                </p>
+              )}
             </div>
           )}
           
-          <button type="submit" style={styles.btn}>登录</button>
+          <button type="submit" style={styles.btn}>🚀 登录出征</button>
         </form>
       </div>
     </div>