Add package.json with express dependency

package.json

@@ -0,0 +1,16 @@
+{
+  "name": "bside-webhook-proxy",
+  "version": "1.0.0",
+  "description": "Multi-project webhook proxy for incoming webhooks (Square, Stripe, GitHub, etc.) that forwards to Appwrite functions with proper auth headers.",
+  "main": "server.js",
+  "scripts": {
+    "start": "node server.js"
+  },
+  "engines": {
+    "node": ">=18.0.0"
+  },
+  "dependencies": {
+    "express": "^4.19.2"
+  },
+  "license": "MIT"
+}