Add site-grouped device list in sidebar

Fetch device sites from /api/v1/deviceSites in parallel with devices,
then group cameras by site with collapsible headers. Search now also
matches site names. Falls back to flat list if sites API is unavailable.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

main.js

@@ -218,6 +218,33 @@ ipcMain.handle('api-get-devices', async (event, { deploymentUrl, cookies }) => {
   }
 });
 
+ipcMain.handle('api-get-device-sites', async (event, { deploymentUrl, cookies }) => {
+  try {
+    const sitesUrl = `${deploymentUrl}/api/v1/deviceSites`;
+
+    const axiosInstance = axios.create({
+      timeout: 10000,
+      headers: {
+        'Cookie': cookies ? cookies.join('; ') : ''
+      }
+    });
+
+    const response = await axiosInstance.get(sitesUrl);
+
+    return {
+      success: true,
+      sites: response.data
+    };
+  } catch (error) {
+    console.error('Get device sites error:', error);
+    return {
+      success: false,
+      sites: [],
+      message: error.response?.data?.message || error.message || 'Failed to get device sites'
+    };
+  }
+});
+
 ipcMain.handle('api-get-auth-info', async (event, { deploymentUrl, cookies }) => {
   try {
     const authUrl = `${deploymentUrl}/api/v1/auth`;