feat: add system configuration (A-03) — map center, zoom, radius min/max

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

app/Http/Controllers/SettingController.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace App\Http\Controllers;
+
+use App\Models\ActivityLog;
+use App\Models\Setting;
+use Illuminate\Http\Request;
+
+class SettingController extends Controller
+{
+    public function index()
+    {
+        return response()->json(Setting::orderBy('id')->get(['key', 'value', 'label']));
+    }
+
+    public function update(Request $request, string $key)
+    {
+        $setting = Setting::where('key', $key)->firstOrFail();
+
+        $request->validate(['value' => 'required|string|max:255']);
+
+        Setting::set($key, $request->value);
+
+        ActivityLog::record('update', "Mengubah konfigurasi: {$setting->label} → {$request->value}", 'setting', $key);
+
+        return response()->json(['success' => true]);
+    }
+}