feat: 增强开奖与设置控制器的币种支持功能

引入 CurrencyResolver，用于在 DrawCurrentController、DrawResultShowController 与 DrawResultsIndexController 中统一处理币种代码解析。
更新 DrawHallSnapshotBuilder 与 DrawResultViewService 的构建方法，新增币种代码参数支持，确保开奖相关功能中的币种处理一致性。
增强 SettingIndexController：新增允许访问的 KV 配置分组校验。
在 OddsStreamService、PlayConfigStreamService 与 RiskCapStreamService 中新增广播功能，用于在玩法目录变更时推送更新通知。
新增测试用例，验证风险限额发布的广播行为。

tests/Feature/PublicSettingsApiTest.php

@@ -0,0 +1,37 @@
+<?php
+
+use App\Lottery\ErrorCode;
+use Database\Seeders\CurrencySeeder;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+
+uses(RefreshDatabase::class);
+
+beforeEach(function (): void {
+    $this->seed(CurrencySeeder::class);
+});
+
+test('public settings requires allowed group', function (): void {
+    $this->getJson('/api/v1/settings')
+        ->assertStatus(400)
+        ->assertJsonPath('code', ErrorCode::ClientHttpError->value);
+
+    $this->getJson('/api/v1/settings?group=wallet')
+        ->assertStatus(400)
+        ->assertJsonPath('code', ErrorCode::ClientHttpError->value);
+});
+
+test('public settings returns frontend group only', function (): void {
+    \App\Models\LotterySetting::query()->updateOrCreate(
+        ['setting_key' => 'frontend.play_rules_html_zh'],
+        [
+            'group_name' => 'frontend',
+            'value_json' => '<p>rules</p>',
+            'description_zh' => '规则',
+        ],
+    );
+
+    $this->getJson('/api/v1/settings?group=frontend')
+        ->assertOk()
+        ->assertJsonPath('code', ErrorCode::Success->value)
+        ->assertJsonFragment(['key' => 'frontend.play_rules_html_zh']);
+});