Migrate billing backend from Django to Express + Apollo Server + Prisma

Replace Python/Django/Graphene with TypeScript/Express/Apollo Server.
Same 2 endpoints (team/m2m), same JWT auth, same TigerBeetle integration.
Prisma ORM replaces Django ORM for Account/OperationCode/ServiceAccount.

package.json

@@ -0,0 +1,31 @@
+{
+  "name": "billing",
+  "version": "1.0.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "tsx watch src/index.ts",
+    "build": "prisma generate && tsc",
+    "start": "prisma migrate deploy && node dist/index.js",
+    "prisma:migrate": "prisma migrate dev"
+  },
+  "dependencies": {
+    "@apollo/server": "^4.11.3",
+    "@prisma/client": "^6.5.0",
+    "cors": "^2.8.5",
+    "express": "^4.21.2",
+    "graphql": "^16.10.0",
+    "graphql-tag": "^2.12.6",
+    "jose": "^6.0.11",
+    "tigerbeetle-node": "^0.16.43",
+    "@sentry/node": "^9.5.0"
+  },
+  "devDependencies": {
+    "@types/cors": "^2.8.17",
+    "@types/express": "^5.0.0",
+    "@types/node": "^22.13.0",
+    "prisma": "^6.5.0",
+    "tsx": "^4.19.0",
+    "typescript": "^5.7.0"
+  }
+}