Enhanced UI and background

Improved UI

Redesign UI: professional dark theme with Constellar branding

Add WhiteNoise to serve static constellation images via gunicorn

Switch to gemini-3.5-flash

Switch to google-genai package

Upgrade google-generativeai to latest; fix REST URL v1beta -> v1

Switch Gemini model to gemini-1.5-flash (free tier compatible)

Fix NoReverseMatch: replace {% url 'chatbot' %} with template variable in home.html

Fix apt package name for Debian Trixie: libgl1-mesa-glx -> libgl1

fix: add HF Spaces README with docker sdk config

initial: predictor service