feat: add event creation script with random slugs

Add reusable script for creating events with secure random slugs.

- Create backend/scripts/create-event.js with CLI interface
- Add npm script 'event:create' to package.json
- Generate 8-character random hex slugs using crypto
- Include date validation and error handling
- Display event details and URL after creation

backend/package.json

@@ -14,7 +14,8 @@
     "prisma:seed:dev": "node prisma/seed.development.js",
     "prisma:seed:prod": "node prisma/seed.production.js",
     "prisma:studio": "prisma studio",
-    "cli": "node src/cli/index.js"
+    "cli": "node src/cli/index.js",
+    "event:create": "node scripts/create-event.js"
   },
   "keywords": [
     "webrtc",