feat(ui): consolidate map filters and rework station selection

- replace inline filter pills with a single "Filters" popover containing
  small pill buttons for fuel/radius/sort/brand (no native <select>s)
- map polish: Carto Positron tiles, hidden zoom buttons, locate-me floating
  button + accuracy ring, smooth flyTo transitions, slim ⓘ attribution
- map markers no longer open Leaflet popups; clicking a marker selects the
  station and surfaces the existing StationCard inline over the map, with
  swipe-down-to-close and a small overlay × button
- price colour now reflects deal quality (cheap / average / expensive vs
  search avg ± 3p) on both list and map — stable across sort/filter
- promote the "X ago" timestamp into the card header so it stays visible
  in the expanded state

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

resources/js/components/StationList.vue

@@ -24,7 +24,7 @@
                     <h3 class="font-black text-zinc-800">Older prices</h3>
                     <span class="text-xs text-zinc-500 font-medium">3–7 days old — verify before driving</span>
                 </header>
-                <div class="opacity-80">
+                <div>
                     <StationCard
                         v-for="station in stale"
                         :key="station.station_id"
@@ -53,7 +53,7 @@
                         icon="lucide:chevron-down"
                     ></iconify-icon>
                 </button>
-                <div v-if="outdatedOpen" class="opacity-60">
+                <div v-if="outdatedOpen">
                     <StationCard
                         v-for="station in outdated"
                         :key="station.station_id"