Comment Mentions: Fixed and tweaks during review of changes

- Added advisory on role permission form to advise which allow listing
  of users/roles.
- Updated database config to avoid PHP8.5 deprecation.
- Tweaked migration to remove unused index.
- Fixed test namespace.

database/migrations/2025_12_15_140219_create_mention_history_table.php

@@ -15,7 +15,7 @@ return new class extends Migration
             $table->increments('id');
             $table->string('mentionable_type', 50)->index();
             $table->unsignedBigInteger('mentionable_id')->index();
-            $table->unsignedInteger('from_user_id')->index();
+            $table->unsignedInteger('from_user_id');
             $table->unsignedInteger('to_user_id');
             $table->timestamps();
         });