feat: resolve full postcodes from local DB before HTTP

tests/Unit/Services/PostcodeServiceTest.php

@@ -1,5 +1,6 @@
 <?php
 
+use App\Models\Postcode;
 use App\Services\ApiLogger;
 use App\Services\LocationResult;
 use App\Services\PostcodeService;
@@ -171,3 +172,25 @@ it('returns null and does not throw on API failure', function (): void {
 
     expect($result)->toBeNull();
 });
+
+// --- Local DB (full postcode) ---
+
+it('resolves a full postcode from local DB without calling HTTP', function (): void {
+    Postcode::create([
+        'postcode' => 'SW1A1AA',
+        'outcode' => 'SW1A',
+        'lat' => 51.501009,
+        'lng' => -0.141588,
+    ]);
+
+    Http::fake(); // any HTTP call will be recorded
+
+    $result = $this->service->resolve('SW1A 1AA');
+
+    expect($result)->toBeInstanceOf(LocationResult::class)
+        ->and($result->displayName)->toBe('SW1A 1AA')
+        ->and($result->lat)->toBe(51.501009)
+        ->and($result->lng)->toBe(-0.141588);
+
+    Http::assertNothingSent();
+});