perf: optimize app startup and background lifecycles

tests/setup.ts

@@ -24,6 +24,7 @@ vi.mock('electron', () => ({
   BrowserWindow: vi.fn(),
   ipcMain: { on: vi.fn(), handle: vi.fn(), removeHandler: vi.fn() },
   dialog: { showOpenDialog: vi.fn(), showMessageBox: vi.fn() },
+  net: { fetch: vi.fn() },
   shell: { openExternal: vi.fn() },
   safeStorage: {
     isEncryptionAvailable: vi.fn().mockReturnValue(true),