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
- Add "Search by city" toggle as alternative to GPS location
- Replace saved cafes button list with select dropdown
- Show editable review form when selecting a Foursquare result
- Guard all datastar-fetch handlers with in-progress signals
- Fix step indicator spacing (mt-4 on steps 2 and 3)
- Add POST /api/v1/check-in endpoint with CheckInSubmission
- nearby_cafes returns HTML fragment for Datastar, JSON for API
- Add NearbyCafeView and NearbyCafesFragment for server-rendered results
- Rewrite checkin.html: replace checkin.js with Datastar signals,
@post for submission, @get for nearby search, inline geolocation JS
- Cafe filtering uses data-show with signal-based search
