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>

open-next.config.ts

@@ -0,0 +1,5 @@
+import { defineCloudflareConfig } from "@opennextjs/cloudflare";
+
+// Minimal config — the project is fully stateless (sessions live on the
+// client), so no R2/KV/D1 incremental cache is needed.
+export default defineCloudflareConfig();