feat: implement AI insights service and settings tab

Add core insight service and IPC handlers; update config and settings page.

Co-authored-by: Jason <159670257+Jasonzhu1207@users.noreply.github.com>

electron/preload.ts

@@ -442,5 +442,11 @@ contextBridge.exposeInMainWorld('electronAPI', {
     start: (port?: number, host?: string) => ipcRenderer.invoke('http:start', port, host),
     stop: () => ipcRenderer.invoke('http:stop'),
     status: () => ipcRenderer.invoke('http:status')
+  },
+
+  // AI 见解
+  insight: {
+    testConnection: () => ipcRenderer.invoke('insight:testConnection'),
+    getTodayStats: () => ipcRenderer.invoke('insight:getTodayStats')
   }
 })