fix(PBI-58): pin turbopack root to cwd so worktrees resolve own node_modules

Multi-lockfile setups (e.g. running dev/build from inside a git worktree
under .claude/worktrees/) caused Next.js to climb up to the parent repo's
package-lock.json and resolve modules from the parent's node_modules,
which doesn't have the new manual-rendering deps installed. Pinning
turbopack.root to process.cwd() keeps each invocation scoped to the
directory it was launched from.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

next.config.ts

@@ -5,6 +5,11 @@ import pkg from "./package.json"
 const nextConfig: NextConfig = {
   reactStrictMode: true,
   serverExternalPackages: ['sharp'],
+  // Pin Turbopack workspace root to the invocation directory so worktrees
+  // resolve their own node_modules instead of climbing into an outer lockfile.
+  turbopack: {
+    root: process.cwd(),
+  },
   env: {
     NEXT_PUBLIC_APP_VERSION: pkg.version,
     NEXT_PUBLIC_BUILD_DATE: new Date().toISOString(),