refactor: 迁移彩票设置至 LotterySettings 服务

- 更新多个控制器和服务，使用 LotterySettings 服务获取彩票相关配置，如默认币种、开奖间隔、下注窗口等，提升代码一致性与可维护性。
- 移除 .env.example 中不再使用的配置项，建议通过后台管理进行设置。

app/Http/Controllers/Api/V1/Admin/Currency/AdminCurrencyDestroyController.php

@@ -7,6 +7,7 @@ use App\Lottery\ErrorCode;
 use App\Support\ApiResponse;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Support\Facades\DB;
+use App\Services\LotterySettings;
 use App\Http\Controllers\Controller;
 
 final class AdminCurrencyDestroyController extends Controller
@@ -15,7 +16,7 @@ final class AdminCurrencyDestroyController extends Controller
     {
         $code = strtoupper((string) $currency->code);
 
-        if ($code === strtoupper((string) config('lottery.default_currency', 'NPR'))) {
+        if ($code === LotterySettings::defaultCurrency()) {
             return ApiResponse::error(
                 '默认币种不可删除',
                 ErrorCode::ValidationFailed->value,

app/Http/Controllers/Api/V1/Admin/Draw/AdminDrawIndexController.php

@@ -8,6 +8,7 @@ use App\Models\TicketItem;
 use App\Models\TicketOrder;
 use Illuminate\Http\Request;
 use App\Support\AdminApiList;
+use App\Services\LotterySettings;
 use Illuminate\Http\JsonResponse;
 use App\Http\Controllers\Controller;
 use Illuminate\Contracts\Pagination\LengthAwarePaginator;
@@ -38,10 +39,10 @@ final class AdminDrawIndexController extends Controller
 
         return AdminApiList::jsonWith($paginator, fn (Draw $row) => $this->row($row), [
             'schedule' => [
-                'timezone' => (string) config('lottery.draw.timezone', 'UTC'),
-                'interval_minutes' => (int) config('lottery.draw.interval_minutes', 5),
-                'betting_window_seconds' => (int) config('lottery.draw.betting_window_seconds', 270),
-                'close_before_draw_seconds' => (int) config('lottery.draw.close_before_draw_seconds', 30),
+                'timezone' => LotterySettings::drawTimezone(),
+                'interval_minutes' => LotterySettings::drawIntervalMinutes(),
+                'betting_window_seconds' => LotterySettings::drawBettingWindowSeconds(),
+                'close_before_draw_seconds' => LotterySettings::drawCloseBeforeDrawSeconds(),
             ],
         ]);
     }