feat(desktop-client): add settings window and switch default API to production

- Open a dedicated settings BrowserWindow with general / login / diagnostics / about tabs
- Persist openAtLogin and keepRunningInBackground via desktop-settings.json; hide main window instead of quitting when background mode is on
- Default API base URL now points to api.shengxintui.com; LoginView and SettingsView share a single constant
- Restore wangyihao session cookies on probe and silent refresh, and accept the legacy http://mp.163.com console origin
- Drop the standalone diagnostics view in favor of the settings tab

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop-client/src/renderer/components/DesktopShell.vue

@@ -6,8 +6,8 @@ import {
   SendOutlined,
   LinkOutlined,
   RobotOutlined,
-  ToolOutlined,
   LogoutOutlined,
+  SettingOutlined,
 } from "@ant-design/icons-vue";
 
 import { useDesktopRuntime } from "../composables/useDesktopRuntime";
@@ -61,13 +61,6 @@ const navItems = computed(() => {
       count: accounts.filter((item) => monitoringIDs.has(item.platform)).length,
       icon: RobotOutlined,
     },
-    {
-      to: "/diagnostics",
-      title: "诊断",
-      description: "vault、scheduler、transport 与原始快照",
-      count: data?.clients.length ?? 0,
-      icon: ToolOutlined,
-    },
   ];
 });
 
@@ -78,6 +71,10 @@ const liveClientLabel = computed(() => snapshot.value?.clients[0]?.deviceName ??
 const clientLabel = computed(
   () => liveClientLabel.value ?? session.value?.desktopClient?.device_name ?? "当前设备尚未注册 client",
 );
+
+function openSettingsWindow() {
+  void window.desktopBridge.app.openSettingsWindow();
+}
 </script>
 
 <template>
@@ -128,11 +125,18 @@ const clientLabel = computed(
                 <span class="device-name-text">{{ clientLabel }}</span>
               </div>
             </a-tooltip>
-            <a-tooltip title="退出登录" placement="top">
-              <button type="button" class="logout-action-btn" @click="logout">
-                <LogoutOutlined />
-              </button>
-            </a-tooltip>
+            <div class="action-cluster">
+              <a-tooltip title="设置" placement="top">
+                <button type="button" class="footer-icon-btn" @click="openSettingsWindow">
+                  <SettingOutlined />
+                </button>
+              </a-tooltip>
+              <a-tooltip title="退出登录" placement="top">
+                <button type="button" class="footer-icon-btn footer-icon-btn--danger" @click="logout">
+                  <LogoutOutlined />
+                </button>
+              </a-tooltip>
+            </div>
           </div>
         </section>
 
@@ -428,7 +432,13 @@ h1 {
   text-overflow: ellipsis;
 }
 
-.logout-action-btn {
+.action-cluster {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.footer-icon-btn {
   width: 32px;
   height: 32px;
   border-radius: 8px;
@@ -441,9 +451,22 @@ h1 {
   border: 1px solid transparent;
   cursor: pointer;
   transition: all 0.2s ease;
+  text-decoration: none;
 }
 
-.logout-action-btn:hover {
+.footer-icon-btn:hover {
+  background: #f1f5f9;
+  color: #1677ff;
+  border-color: #e2e8f0;
+}
+
+.footer-icon-btn.router-link-active {
+  background: #e6f4ff;
+  color: #1677ff;
+  border-color: #e6f4ff;
+}
+
+.footer-icon-btn--danger:hover {
   background: #fef2f2;
   color: #ef4444;
   border-color: #fee2e2;