test(server): drain Git traces before fixture cleanup

The missing-folder observation test deletes its trace directory while a queued diagnostic append can still recreate the trace file, producing ENOTEMPTY in CI. Drain the trace queue after service shutdown and before removing the fixture.

packages/server/src/server/workspace-git-service.observation.integration.test.ts

@@ -871,6 +871,7 @@ test.skipIf(process.platform !== "linux")(
     } finally {
       subscription.unsubscribe();
       await service.dispose();
+      await flushGitCommandTrace();
       if (previousTrace === undefined) delete process.env.PASEO_GIT_TRACE_FILE;
       else process.env.PASEO_GIT_TRACE_FILE = previousTrace;
       rmSync(root, { recursive: true, force: true });