Add full-stack launcher, walkthrough demo, and production polish

[rwilliamspbg-ops]

This PR introduces:

1. An interactive full-stack CLI launch manager (launch.py and launch.sh) with an animated ASCII eagle splash screen, system environment checks, local and Docker orchestration, and custom signal handling.
2. An immersive, terminal-based walkthrough 'video' demo directly playable from the launcher, showcasing the entire end-to-end installation, keygen, loading, chat streaming, and worker mDNS auto-discovery.
3. Production polishing to gui_backend.py including dynamic host resource metrics using psutil and configurable worker routing via environment variables.
4. Auto-formatted code with black/isort, and verified 100% test completion (33/33 tests passing natively).

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PR created automatically by Jules for task 13715830416526598496 started by @rwilliamspbg-ops

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