refactor: flatten monorepo to single web package (#12)

Flatten the pnpm monorepo (apps/web + packages/*) into a single web package at the repo root.

- Move app/lib/components/scripts/public to root; drop apps/web and packages/* wrappers
- Rewrite tsconfig paths (@infiplot/*) to ./lib/*; turbopack.root = __dirname
- Update Vercel (no root-directory) and Cloudflare (pnpm build:cf at root) deploy paths
- Regenerate pnpm-lock.yaml to drop stale workspace importers
- Bump engines.node to >=22 to match wrangler

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

vercel.json

@@ -0,0 +1,11 @@
+{
+  "$schema": "https://openapi.vercel.sh/vercel.json",
+  "framework": "nextjs",
+  "functions": {
+    "app/api/start/route.ts":       { "maxDuration": 60 },
+    "app/api/scene/route.ts":       { "maxDuration": 60 },
+    "app/api/vision/route.ts":      { "maxDuration": 60 },
+    "app/api/insert-beat/route.ts": { "maxDuration": 60 },
+    "app/api/beat-audio/route.ts":  { "maxDuration": 30 }
+  }
+}