Reverse-geocode a general area label for logged searches

Each search now stores an `area_label` (district/town) reverse-geocoded from its
coarsened ~1km lat/lng bucket via postcodes.io, surfaced in the Filament Searches
admin as a sortable/searchable column plus an area filter. Geocoding is cached 30
days per bucket, queries a 2km radius so low-density buckets still match the
default 100m miss, and fails gracefully to null. Adds `searches:backfill-areas`
(scheduled hourly) to label existing rows and retry stragglers.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/Filament/Resources/Searches/SearchResource.php

@@ -28,6 +28,11 @@ class SearchResource extends Resource
                     ->label('Searched At')
                     ->dateTime('d M Y H:i')
                     ->sortable(),
+                TextColumn::make('area_label')
+                    ->label('Area')
+                    ->placeholder('Unknown')
+                    ->searchable()
+                    ->sortable(),
                 TextColumn::make('fuel_type')
                     ->label('Fuel Type')
                     ->badge(),
@@ -67,6 +72,15 @@ class SearchResource extends Resource
                         'B10' => 'B10',
                         'HVO' => 'HVO',
                     ]),
+                SelectFilter::make('area_label')
+                    ->label('Area')
+                    ->searchable()
+                    ->options(fn (): array => Search::query()
+                        ->whereNotNull('area_label')
+                        ->distinct()
+                        ->orderBy('area_label')
+                        ->pluck('area_label', 'area_label')
+                        ->all()),
             ])
             ->recordActions([])
             ->toolbarActions([]);