fix: 鉴权改为全屏登录页模式，未登录不再暴露主页面内容，增加退出登录按钮

static/css/style.css

@@ -123,6 +123,102 @@ body {
     transition: background-color var(--td-transition), color var(--td-transition);
 }
 
+/* ==================== 登录页面 ==================== */
+.login-page {
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    background: var(--td-bg-color-page);
+    z-index: 10001;
+}
+
+.login-container {
+    width: 380px;
+    padding: 48px 40px;
+    background: var(--td-bg-color-container);
+    border-radius: var(--td-radius-large);
+    box-shadow: var(--td-shadow-3);
+    text-align: center;
+}
+
+.login-logo {
+    font-size: 56px;
+    margin-bottom: 8px;
+    line-height: 1;
+}
+
+.login-title {
+    font-size: 22px;
+    font-weight: 700;
+    color: var(--td-text-color-primary);
+    margin-bottom: 4px;
+    letter-spacing: 0.5px;
+}
+
+.login-subtitle {
+    font-size: 14px;
+    color: var(--td-text-color-secondary);
+    margin-bottom: 32px;
+}
+
+.login-form {
+    text-align: left;
+}
+
+.login-form .form-group label {
+    display: block;
+    margin-bottom: 6px;
+    font-size: 13px;
+    font-weight: 500;
+    color: var(--td-text-color-primary);
+}
+
+.login-form .form-input {
+    width: 100%;
+    height: 40px;
+    padding: 0 12px;
+    border: 1px solid var(--td-border-color);
+    border-radius: var(--td-radius-default);
+    font-size: 14px;
+    color: var(--td-text-color-primary);
+    background: var(--td-bg-color-container);
+    transition: all var(--td-transition);
+}
+
+.login-form .form-input:focus {
+    outline: none;
+    border-color: var(--td-brand-color);
+    box-shadow: 0 0 0 2px var(--td-brand-color-focus);
+}
+
+/* ==================== 退出登录按钮 ==================== */
+.logout-btn {
+    width: 32px;
+    height: 32px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border: 1px solid var(--td-border-color);
+    background: var(--td-bg-color-container);
+    color: var(--td-text-color-secondary);
+    border-radius: var(--td-radius-default);
+    cursor: pointer;
+    font-size: 16px;
+    transition: all var(--td-transition);
+    flex-shrink: 0;
+}
+
+.logout-btn:hover {
+    border-color: var(--td-error-color);
+    color: var(--td-error-color);
+    background: var(--td-error-color-light);
+}
+
 /* 滚动条 */
 ::-webkit-scrollbar {
     width: 8px;