feat: add user preferences and saved stations API endpoints

Adds authenticated endpoints for reading/updating fuel type preferences and managing saved stations, backed by new migrations and a SavedStation model.

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

app/Http/Controllers/Api/UserController.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace App\Http\Controllers\Api;
+
+use App\Http\Controllers\Controller;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+use Illuminate\Http\Response;
+use Illuminate\Validation\Rule;
+
+final class UserController extends Controller
+{
+    public function preferences(Request $request): JsonResponse
+    {
+        return response()->json([
+            'preferred_fuel_type' => $request->user()->preferred_fuel_type,
+            'postcode' => $request->user()->postcode,
+        ]);
+    }
+
+    public function updatePreferences(Request $request): JsonResponse
+    {
+        $validated = $request->validate([
+            'preferred_fuel_type' => ['sometimes', Rule::in(['petrol', 'diesel', 'e5', 'b7_premium', 'b10', 'hvo'])],
+            'postcode' => ['sometimes', 'string', 'max:8'],
+        ]);
+
+        $request->user()->update($validated);
+
+        return response()->json([
+            'preferred_fuel_type' => $request->user()->fresh()->preferred_fuel_type,
+            'postcode' => $request->user()->fresh()->postcode,
+        ]);
+    }
+
+    public function savedStations(Request $request): JsonResponse
+    {
+        $stations = $request->user()->savedStations()->get();
+
+        return response()->json(['data' => $stations]);
+    }
+
+    public function saveStation(Request $request): JsonResponse
+    {
+        $validated = $request->validate([
+            'station_id' => ['required', 'string', 'max:64'],
+        ]);
+
+        $request->user()->savedStations()->firstOrCreate([
+            'station_id' => $validated['station_id'],
+        ]);
+
+        return response()->json(null, 201);
+    }
+
+    public function removeStation(Request $request, string $stationId): Response
+    {
+        $request->user()->savedStations()->where('station_id', $stationId)->delete();
+
+        return response()->noContent();
+    }
+}