fix(vercel): configure Turborepo monorepo build for apps/web

- Add vercel.json to apps/web with Turborepo build command
- Configure build to use turbo build --filter=@tpmjs/web
- Ensures Vercel properly detects and builds Next.js app in monorepo structure
- Fixes API routes timing out due to incorrect project root detection

This resolves the issue where Vercel wasn't detecting the Next.js app
inside apps/web/, causing API routes to never be built as serverless functions.

Note: You must also set Root Directory to "apps/web" in Vercel dashboard:
Project Settings > General > Root Directory

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/web/vercel.json

@@ -0,0 +1,5 @@
+{
+  "$schema": "https://openapi.vercel.sh/vercel.json",
+  "buildCommand": "cd ../.. && turbo build --filter=@tpmjs/web",
+  "installCommand": "pnpm install"
+}