- Register the 8 new placeholder apps in DEMO_MOCK_UI so they're launchable
and installable in the demo.
- Demo bypasses the new-tab/tab-launch lists for demoable apps — they're
served same-origin by the mock backend with no framing headers, so they
render in the in-app session instead of opening broken localhost tabs.
- Non-demoable apps now say 'Not available in demo' instead of 'No demo'.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>