Add radio embed widget, SSE real-time, song history, moderation panel, and Auto DJ

- Embed widget: standalone iframe player with dark/light/transparent themes, copy-paste embed code admin page
- Real-time SSE: streaming now-playing/listeners/dj events, replaces polling in radio-player and embed
- Song history: auto-records song changes to radio_song_plays table, Filament resource to view
- DJ moderation: unified panel for shouts approval, song request queue, DJ applications
- Auto DJ: playlist management with round-robin playback when no DJ is live
- Refactored radio-player Alpine component to use EventSource API with auto-reconnect

app/Filament/Resources/RadioSongPlay/Pages/ManageRadioSongPlays.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Filament\Resources\RadioSongPlay\Pages;
+
+use App\Filament\Resources\RadioSongPlay\RadioSongPlayResource;
+use Filament\Resources\Pages\ManageRecords;
+
+class ManageRadioSongPlays extends ManageRecords
+{
+    #[\Override]
+    protected static string $resource = RadioSongPlayResource::class;
+}