fix: generate Prisma client before TypeScript build

The build was failing because Prisma client types weren't being generated
before running tsc. This caused errors like:

- Module '"@prisma/client"' has no exported member 'User'
- Property 'role' does not exist on type 'User'
- Property 'id' does not exist on type 'User'

Changed the build script from:
  "build": "tsc"
To:
  "build": "prisma generate && tsc"

This ensures the Prisma client is generated with all model types before
TypeScript compilation.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

packages/api/package.json

@@ -5,7 +5,7 @@
   "main": "dist/index.js",
   "scripts": {
     "dev": "tsx watch src/index.ts",
-    "build": "tsc",
+    "build": "prisma generate && tsc",
     "start": "node dist/index.js",
     "test": "vitest run",
     "test:watch": "vitest",