feat: add StationTaggingService with supermarket detection

app/Services/StationTaggingService.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace App\Services;
+
+use App\Models\Station;
+
+class StationTaggingService
+{
+    /** @var array<string, string> brand keyword → normalised brand name */
+    private const SUPERMARKET_BRANDS = [
+        'tesco'     => 'Tesco',
+        'asda'      => 'Asda',
+        'morrisons' => 'Morrisons',
+        'sainsbury' => 'Sainsbury\'s',
+        'aldi'      => 'Aldi',
+        'lidl'      => 'Lidl',
+        'costco'    => 'Costco',
+    ];
+
+    public function tag(Station $station): void
+    {
+        $name = strtolower($station->trading_name);
+
+        foreach (self::SUPERMARKET_BRANDS as $keyword => $normalisedBrand) {
+            if (str_contains($name, $keyword)) {
+                $station->is_supermarket = true;
+                $station->brand_name     = $normalisedBrand;
+                return;
+            }
+        }
+    }
+}