feat: add read-only Sites API

Add GET /api/sites endpoint for listing sites with optional name filter,
and GET /api/sites/{site} for showing individual sites. Includes API
resource, controller, routes registration, and comprehensive tests.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/Http/Controllers/Api/SiteController.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Http\Controllers\Api;
+
+use App\Http\Controllers\Controller;
+use App\Http\Resources\SiteResource;
+use App\Models\Site;
+use Illuminate\Http\Request;
+
+class SiteController extends Controller
+{
+    public function index(Request $request)
+    {
+        $query = Site::query();
+
+        if ($request->filled('name')) {
+            $query->where('name', 'like', '%' . $request->string('name') . '%');
+        }
+
+        return SiteResource::collection($query->orderBy('name')->get());
+    }
+
+    public function show(Site $site)
+    {
+        return new SiteResource($site);
+    }
+}