feat: add postcode resolution to /api/stations and Filament SearchResource

Extends NearbyStationsRequest to accept `postcode` (full or outcode) as an alternative to lat/lng. PostcodeService resolves it via postcodes.io and falls through to coordinates. Also adds SearchResource to the Filament admin panel for viewing logged search activity with fuel type filter and price/distance stats columns. Includes SQLite GREATEST/LEAST function polyfills in AppServiceProvider for test compatibility.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

bootstrap/app.php

@@ -3,6 +3,7 @@
 use Illuminate\Foundation\Application;
 use Illuminate\Foundation\Configuration\Exceptions;
 use Illuminate\Foundation\Configuration\Middleware;
+use Illuminate\Http\Request;
 
 return Application::configure(basePath: dirname(__DIR__))
     ->withRouting(
@@ -15,5 +16,5 @@ return Application::configure(basePath: dirname(__DIR__))
         //
     })
     ->withExceptions(function (Exceptions $exceptions): void {
-        //
+        $exceptions->shouldRenderJsonWhen(fn (Request $request) => $request->is('api/*'));
     })->create();