refactor(desktop): extract IPC channels and handlers into src/ipc/

surfsense_desktop/src/ipc/handlers.ts

@@ -0,0 +1,19 @@
+import { app, ipcMain, shell } from 'electron';
+import { IPC_CHANNELS } from './channels';
+
+export function registerIpcHandlers(): void {
+  ipcMain.on(IPC_CHANNELS.OPEN_EXTERNAL, (_event, url: string) => {
+    try {
+      const parsed = new URL(url);
+      if (parsed.protocol === 'http:' || parsed.protocol === 'https:') {
+        shell.openExternal(url);
+      }
+    } catch {
+      // invalid URL — ignore
+    }
+  });
+
+  ipcMain.handle(IPC_CHANNELS.GET_APP_VERSION, () => {
+    return app.getVersion();
+  });
+}