Add ability to save edited images with overlays to the media library

Implement a new endpoint for uploading edited images, converting them to a JPEG blob using html2canvas, and storing them in Cloudinary.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/397bca8c-984f-43ff-841a-10897aeb8140/ae4037a0-2a6f-4530-9bac-79b543286bda/VEZwUqa

package.json

@@ -63,6 +63,7 @@
     "express": "^4.21.2",
     "express-session": "^1.18.1",
     "framer-motion": "^11.13.1",
+    "html2canvas": "^1.4.1",
     "input-otp": "^1.4.2",
     "lucide-react": "^0.453.0",
     "memorystore": "^1.6.7",