Adjust color palette to reflect new amber branding across all
documentation components including hero section gradients, button
shadows, focus states, and dark mode variants. Updated CSS variables
and RGBA color values throughout custom.scss and _variables.html.
This commit introduces a new script `dev/generate-logo.sh` along with its prompt `dev/logo-prompt.json` to create logo variants.
It updates the documentation to:
- Reference the new PNG logo files instead of the old SVG.
- Include `logo-variant-*.png` in the `.gitignore`.
- Update the favicon to use the new logo's style.
- Adjust CSS for logo display and hero image.