fix(web): set page title on chat embed pages (#4820)

Set a translated page title on the readonly and readwrite chat embed
pages so popout/embedded chat windows display a meaningful title
based on the configured stream name, addressing #4794.

Uses next-export-i18n with a new chatEmbedTitle key for proper
localization. Also fixes the readonly embed error boundary
componentName from ReadWriteChatEmbed to ReadOnlyChatEmbed.

web/i18n/en/translation.json

@@ -221,7 +221,8 @@
 		"offlineBasic": "This stream is offline. Check back soon!",
 		"offlineFediverseOnly": "This stream is offline. <span class='follow-link'>Follow</span> {{fediverseAccount}} on the Fediverse to see the next time {{streamer}} goes live.",
 		"offlineNotifyAndFediverse": "This stream is offline. You can <span class='notify-link'>be notified</span> the next time {{streamer}} goes live or <span class='follow-link'>follow</span> {{fediverseAccount}} on the Fediverse.",
-		"offlineNotifyOnly": "This stream is offline. <span class='notify-link'>Be notified</span> the next time {{streamer}} goes live."
+		"offlineNotifyOnly": "This stream is offline. <span class='notify-link'>Be notified</span> the next time {{streamer}} goes live.",
+		"chatEmbedTitle": "{{name}} Chat"
 	},
 	"Testing": {
 		"itemCount": "You have {{count}} items",
@@ -229,4 +230,4 @@
 		"noPluralKey": "This key has no plural variants - {{count}} things",
 		"simpleKey": "Simple translation text"
 	}
-}
+}