Log event creation to admin audit log, add back button, bump to 1.10.3

createEvent never called logAdminAction, even though 1.10.0 already
listed event_created as a filterable action on the audit-log page —
only updateEvent/deleteEvent actually logged. Event creation is now
logged the same way, at every return path including the legacy
pre-migration retry branches.

Also adds a "Back to dashboard" link to Admin -> Audit log, matching
the existing back-link pattern on the Cashup page.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSWFWQsjTc9GyffPiXEDQT

backend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "event-management-backend",
-  "version": "1.10.2",
+  "version": "1.10.3",
   "description": "Event Management System Backend",
   "main": "src/index.js",
   "scripts": {