feat: implement Phase 5 system handlers (automation, power, recording)

- Implement window control, wallpaper reset, and power management.
- Add Aperture recording wrapper and displayplacer layout control.
- Add self-update logic stub for local/remote sources.
- Register and expose handlers via context bridge.

src/main/index.ts

@@ -5,6 +5,7 @@ import { loadSeedConfig } from './config_loader';
 import { fetchFullConfig } from './api_client';
 import { registerShellHandlers } from './shell_handlers';
 import { registerFileHandlers } from './file_handlers';
+import { registerSystemHandlers } from './system_handlers';
 import { SeedConfig } from '../shared/types';
 
 let mainWindow: BrowserWindow | null = null;
@@ -48,6 +49,8 @@ async function createWindow() {
 
 registerShellHandlers();
 registerFileHandlers();
+registerSystemHandlers();
+
 app.on('ready', createWindow);
 
 app.on('window-all-closed', () => {