enhance: metaをSSR HTMLに埋め込む (#13436)

* enhance: `meta`をSSR HTMLに埋め込む

* HTML Metaの有効時間を指定

* １時間

* MetaEntityService

* JSONをPackするように

* ✌️

---------

Co-authored-by: syuilo <4439005+syuilo@users.noreply.github.com>

packages/backend/src/server/web/views/base.pug

@@ -68,6 +68,9 @@ html
 			var VERSION = "#{version}";
 			var CLIENT_ENTRY = "#{clientEntry.file}";
 
+		script(type='application/json' id='misskey_meta' data-generated-at=now)
+			!= metaJson
+
 		script
 			include ../boot.js