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

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

database/migrations/2026_06_05_000000_create_settings_table.php

@@ -0,0 +1,39 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void
+    {
+        Schema::create('settings', function (Blueprint $table) {
+            $table->id();
+            $table->string('key')->unique();
+            $table->string('value');
+            $table->string('label');
+            $table->timestamps();
+        });
+
+        // Default values
+        $defaults = [
+            ['key' => 'map_center_lat',   'value' => '-0.0553',  'label' => 'Pusat Peta — Latitude'],
+            ['key' => 'map_center_lng',   'value' => '109.3463', 'label' => 'Pusat Peta — Longitude'],
+            ['key' => 'map_default_zoom', 'value' => '17',       'label' => 'Zoom Default Peta'],
+            ['key' => 'radius_min',       'value' => '50',       'label' => 'Radius Minimum (meter)'],
+            ['key' => 'radius_max',       'value' => '2000',     'label' => 'Radius Maksimum (meter)'],
+        ];
+
+        foreach ($defaults as $row) {
+            \DB::table('settings')->insert(array_merge($row, [
+                'created_at' => now(),
+                'updated_at' => now(),
+            ]));
+        }
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('settings');
+    }
+};