test(desktop): widen the execProbe event-loop test timeout

The 'execProbe keeps the parent event loop available' case asserts nothing
about timing; the 1s spawn budget only exists so a wedged child cannot stall
the run. A cold Windows CI runner can take longer than 1s just to start the
node child, which failed the test for reasons unrelated to what it guards.
5s keeps the safety bound without the flake.

apps/desktop/electron/backend-probes.test.ts

@@ -66,7 +66,7 @@ test('execProbe keeps the parent event loop available to the child', async () =>
   try {
     await execProbe(NODE_BIN, ['-e', childScript], {
       stdio: 'ignore',
-      timeout: 1_000,
+      timeout: 5_000,
       windowsHide: true
     })
   } finally {