fix(launcher): handle detached app spawn errors

- Log detached app launch failures before releasing the child process

src/main-entry-runtime.test.ts

@@ -37,7 +37,10 @@ test('detached app launch policy stays in the startup runtime utilities', () =>
 
   assert.equal(typeof spawnDetachedApp, 'function');
   assert.doesNotMatch(entrySource, /function spawnDetachedApp/);
-  assert.match(runtimeSource, /child\.unref\(\)/);
+  assert.match(
+    runtimeSource,
+    /child\.once\('error', \(error\) => \{\s*console\.error\([^;]*error\);\s*\}\);\s*child\.unref\(\)/,
+  );
 });
 
 test('background bootstrap exits through Electron so Chromium children shut down', () => {

src/main-entry-runtime.ts

@@ -280,6 +280,9 @@ export function spawnDetachedApp(childArgs: string[], env: NodeJS.ProcessEnv): v
         stdio: 'ignore',
         env,
       });
+  child.once('error', (error) => {
+    console.error('Failed to spawn detached SubMiner app:', error);
+  });
   child.unref();
 }