fix: handle async FSWatcher errors in project customization watcher

On Linux, fs.watch() on a non-existent directory emits an asynchronous
'error' event instead of throwing synchronously. Without an error handler,
this crashes the process. Tests that create AryxAppService with fake
project paths (e.g. C:\workspace\project-one) trigger this on Linux CI
because those paths don't exist.

Attach an 'error' event handler to the FSWatcher that logs a warning and
closes the watcher gracefully. This fixes the Linux CI 'bun test' failure
and also prevents production crashes if a watched directory is deleted
at runtime.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/services/projectCustomizationWatcher.ts

@@ -169,7 +169,14 @@ async function collectExistingDirectories(rootPath: string): Promise<string[]> {
 }
 
 function createProjectWatchHandle(directoryPath: string, onChange: () => void): ProjectWatchHandle {
-  return watch(directoryPath, { persistent: false }, () => {
+  const watcher = watch(directoryPath, { persistent: false }, () => {
     onChange();
   });
+
+  watcher.on('error', (error) => {
+    console.warn(`[aryx customization] Watcher error for ${directoryPath}:`, error);
+    watcher.close();
+  });
+
+  return watcher;
 }