Launch and generate from the local LUT workspace

[Today20092]

What to build

Give a filmmaker a downloadable-app-style local workspace that launches from Windows, opens in their default browser, and generates a valid LUT without exposing a network service or requiring terminal interaction.

The launcher should start the Python application on an available loopback-only port, open a system-themed Shadcn workspace with the approved useful middle-grey default, and keep a visible console window open until the user stops it. Generation must reuse the existing LutSetup validation and LUT engine.

Acceptance criteria

• Launching the application binds only to 127.0.0.1 on an available port, opens the default browser, prints clear status and shutdown instructions, and exits cleanly on Enter or Ctrl+C.
• The browser displays a responsive, system-themed Shadcn workspace initialized to Sony S-Log3 to Rec.709, cube size 65, Stops mode, one suggested 0-stop band at standard width, monochrome enabled, and full range.
• Generating the default setup downloads a valid .cube file produced by the existing engine.
• Mutation requests require JSON and a per-launch token, output names are reduced to safe .cube basenames, and temporary generation files are removed after the response is prepared.
• Existing CLI behavior and tests remain green, with an integration check covering local bootstrap and default LUT generation.

Blocked by

None - can start immediately.