Update webhook integration to use JSON instead of form-data

Removes the use of the `form-data` package and modifies the webhook payload to send data as JSON.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: cfbfe47c-0c9a-4ebf-8a41-2937407eccff
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/cfbfe47c-0c9a-4ebf-8a41-2937407eccff/uD8abDf

package.json

@@ -43,7 +43,6 @@
     "@radix-ui/react-tooltip": "^1.2.0",
     "@tanstack/react-query": "^5.60.5",
     "@types/bcrypt": "^6.0.0",
-    "@types/form-data": "^2.2.1",
     "@types/memoizee": "^0.4.12",
     "@types/node-fetch": "^2.6.13",
     "@types/pg": "^8.15.4",
@@ -61,7 +60,6 @@
     "express": "^4.21.2",
     "express-rate-limit": "^7.5.1",
     "express-session": "^1.18.1",
-    "form-data": "^4.0.4",
     "framer-motion": "^11.13.1",
     "iconv-lite": "^0.6.3",
     "input-otp": "^1.4.2",