fix: set desktopState.backendReady to true in onReady callback

The onReady callback updated the internal manager state's ready field
but never set desktopState.backendReady to true. The ref was only ever
set to false (on start, finalize, and stop), so any consumer reading
desktopState.backendReady would always see false even after the backend
was confirmed ready via HTTP.

Also removed the manual workaround in the test that set backendReady
to true externally.

Author: cursoragent

apps/desktop/src/backend/DesktopBackendManager.test.ts

@@ -328,7 +328,6 @@ describe("DesktopBackendManager", () => {
         yield* manager.start;
         assert.equal(yield* Queue.take(startedPids), 123);
         yield* Deferred.await(ready);
-        yield* Ref.set(backendReady, true);
         assert.isTrue(yield* Ref.get(backendReady));
         assert.deepEqual(yield* manager.currentConfig, Option.some(baseConfig));
 

apps/desktop/src/backend/DesktopBackendManager.ts

@@ -443,6 +443,7 @@ const makeDesktopBackendManager = Effect.fn("makeDesktopBackendManager")(functio
                   onSome: (run) => (run.id === runId ? true : latest.ready),
                 }),
               }));
+              yield* Ref.set(desktopState.backendReady, true);
               yield* desktopWindow.handleBackendReady.pipe(
                 Effect.catch((error) =>
                   Effect.logError("failed to open main window after backend readiness").pipe(