refactor(ui): comprehensive light mode fixes and dashboard cleanup
- Light mode: fix 40+ missing CSS overrides (solid emerald/cyan bg-950,
300-level text colours, border opacity variants, hover states, violet
accent, bg-slate-900/30 and /90, bg-rose-950/30, red-950/50)
- Light mode: fix broad bg-gradient-to-br override to only target dark
banner cards (from-[#1E293B]), preserving coloured user avatar gradients
- Light mode: BookingDetailsModal JSON panel switched to GitHub-Light style
(bg #f6f8fa) including <pre> override so the general 'pre' rule cannot
darken it back
- Dashboard: simplify banner (flat card, no gradient/watermark/time-widget)
- Dashboard: reduce visual noise (shorter titles, remove LIVE animated badge,
remove italic notes quote, neutral checklist items, no footer jargon)
- Dashboard: normalise section-icon colours to slate-400 except Active (emerald)
- Dashboard: replace non-standard Tailwind classes (slate-101/350/905/1000,
indigo-405, emerald-990) with valid equivalents
- Dashboard: standardise button style to rounded-lg + text-xs across
Active Reservations and Upcoming cards; add visible borders on Cancel/Purge
7afb4829bc