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/Services/Draw/DrawPlannerService.php

@@ -5,6 +5,7 @@ namespace App\Services\Draw;
 use Carbon\Carbon;
 use App\Models\Draw;
 use App\Lottery\DrawStatus;
+use App\Services\LotterySettings;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Database\QueryException;
 
@@ -21,9 +22,9 @@ final class DrawPlannerService
     public function ensureBuffer(?Carbon $now = null): array
     {
         $nowUtc = ($now ?? Carbon::now())->utc();
-        $tz = (string) config('lottery.draw.timezone', 'UTC');
-        $interval = (int) config('lottery.draw.interval_minutes', 5);
-        $buffer = (int) config('lottery.draw.buffer_draws_ahead', 8);
+        $tz = LotterySettings::drawTimezone();
+        $interval = LotterySettings::drawIntervalMinutes();
+        $buffer = LotterySettings::drawBufferDrawsAhead();
         $maxSeq = intdiv(24 * 60, $interval);
 
         $upcoming = Draw::query()