feat: 添加实时广播功能，支持风险预警、玩法切换和赔率更新，增强大厅公共频道的广播能力

app/Events/OddsUpdateBroadcast.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace App\Events;
+
+use Illuminate\Broadcasting\Channel;
+use Illuminate\Queue\SerializesModels;
+use Illuminate\Foundation\Events\Dispatchable;
+use Illuminate\Broadcasting\InteractsWithSockets;
+use Illuminate\Contracts\Broadcasting\ShouldBroadcastNow;
+
+/**
+ * 界面文档 §2.1：`odds.update` —— 赔率变更推送。
+ *
+ * 触发时机：后台发布新赔率版本时。
+ * 前端处理：Toast 提示用户赔率已更新，建议重新预览注单。
+ */
+final class OddsUpdateBroadcast implements ShouldBroadcastNow
+{
+    use Dispatchable, InteractsWithSockets, SerializesModels;
+
+    /**
+     * @param  int  $versionId  新版本 ID
+     * @param  string  $versionName  版本名称/描述
+     * @param  array<string, mixed>|null  $diff  差异数据（哪些玩法赔率变化了，可选）
+     * @param  int  $emittedAtMs  发送时间戳（毫秒）
+     */
+    public function __construct(
+        public readonly int $versionId,
+        public readonly string $versionName,
+        public readonly ?array $diff,
+        public readonly int $emittedAtMs,
+    ) {}
+
+    /**
+     * 公共频道，所有在大厅的玩家都能收到。
+     *
+     * @return array<int, Channel>
+     */
+    public function broadcastOn(): array
+    {
+        return [new Channel('lottery-hall')];
+    }
+
+    public function broadcastAs(): string
+    {
+        return 'odds.update';
+    }
+
+    /**
+     * @return array{version_id: int, version_name: string, diff: array<string, mixed>|null, message: string, emitted_at_ms: int}
+     */
+    public function broadcastWith(): array
+    {
+        return [
+            'version_id' => $this->versionId,
+            'version_name' => $this->versionName,
+            'diff' => $this->diff,
+            'message' => '赔率已更新，请重新预览注单',
+            'emitted_at_ms' => $this->emittedAtMs,
+        ];
+    }
+}