Overhaul the web UI with CSS custom property-based theming and
dark mode support. Extract reusable template partials (location
search, scan input) and web components (photo-capture,
searchable-select). Add version and commit info to page footer.
- Replace hardcoded amber palette with semantic theme tokens
- Add dark mode with localStorage persistence and system preference detection
- Extract <brew-photo-capture> and <searchable-select> web components
- Extract location_search and scan_input Askama macros
- Add sun/moon, timeline, database, map icons
- Display version and git commit in footer
- Improve timeline coordinate rounding and map link formatting
- Add roast_name, roaster_name, remaining to BagOptionView
