fix: use wasChanged() instead of isDirty() in updated hooks

Critical Bug Fix:
- isDirty() always returns false in updated() hook
- wasChanged() correctly tracks modifications after save

Files Fixed:
- ServerSetting: Sentinel restart now triggers on config changes
- DeletesUserSessions: Session invalidation now works on password change

Security Impact:
- CRITICAL: Password changes now properly invalidate user sessions
- Prevents session hijacking after password reset

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/Traits/DeletesUserSessions.php

@@ -26,7 +26,7 @@ trait DeletesUserSessions
     {
         static::updated(function ($user) {
             // Check if password was changed
-            if ($user->isDirty('password')) {
+            if ($user->wasChanged('password')) {
                 $user->deleteAllSessions();
             }
         });