chore: add changeset for platform notifications admin (#3324)

Author: deepshekhardas

.changeset/platform-notifications-admin.md

@@ -0,0 +1,7 @@
+---
+"@trigger.dev/webapp": patch
+---
+
+feat(webapp): Platform notifications admin improvements
+
+Adds responsive design improvements, enhanced notification management (create, edit, delete, publish-now), organization/project-scoped features, and improved filtering logic for inactive notifications.