メンションの最大数をロールごとに設定可能にする (#13343)

* Add new role policy: maximum mentions per note

* fix

* Reviewを反映

* fix

* Add ChangeLog

* Update type definitions

* Add E2E test

* CHANGELOG に説明を追加

---------

Co-authored-by: taichan <40626578+tai-cha@users.noreply.github.com>

packages/backend/src/models/json-schema/role.ts

@@ -160,6 +160,10 @@ export const packedRolePoliciesSchema = {
 			type: 'boolean',
 			optional: false, nullable: false,
 		},
+		mentionLimit: {
+			type: 'integer',
+			optional: false, nullable: false,
+		},
 		canInvite: {
 			type: 'boolean',
 			optional: false, nullable: false,