Fix file retention after updates on macOS #417

This fixes issue #417 where autoupdate installer files were not deleted
on macOS, leading to accumulation of old installers.

Key changes:

- Store update files in application-specific directory
- Clear update files directory on every app launch

Other supporting changes:

- Refactor file system operations to be more testable and reusable
- Improve separation of concerns in directory management
- Enhance dependency injection for auto-update logic
- Fix async completion to support `await` operations
- Add additional logging and revise some log messages during updates

src/presentation/electron/main/index.ts

@@ -97,7 +97,7 @@ if (isDevelopment) {
   }
 }
 
-function loadApplication(window: BrowserWindow) {
+function loadApplication(window: BrowserWindow): void {
   if (RENDERER_URL) { // Populated in a dev server during development
     loadUrlWithNodeWorkaround(window, RENDERER_URL);
   } else {