Remove the transient Studio desktop auth handoff (#7542)

* Remove Studio desktop auth handoff flash

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

tests/studio/test_desktop_reliability_frontend_contract.py

@@ -98,6 +98,18 @@ def test_chat_exports_await_native_saves_and_markdown_uses_shared_helper():
     assert "downloadFile(" in thread
 
 
+def test_desktop_startup_waits_for_auth_without_intermediate_handoff():
+    source = APP_PROVIDER.read_text(encoding = "utf-8")
+
+    assert 'const showApp = status === "running" && desktopAuthReady;' in source
+    assert "Preparing Unsloth" not in source
+    assert "Signing in to desktop session" not in source
+    assert "desktopBooting" not in source
+    assert "showInteractiveApp" not in source
+    assert "<NativeIntentDrain />" in source
+    assert "{children}" in source
+
+
 def test_full_app_layout_uses_its_own_initialized_marker():
     source = APP_PROVIDER.read_text(encoding = "utf-8")