Adds the Umami session recorder (recorder.js) that powers heatmaps,
alongside the existing analytics tracker. Loaded via next/script with
the same data-domains guard as the main tracker so it only fires on the
production hostnames — staging runs the same image under a different
host and must not feed the heatmap.
Cookieless: recorder.js uses Umami's server-side session model (no
cookie or local storage on the device), so it adds no new PECR
consent trigger.
Verified with tsc --noEmit and next build.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0146VHeLAWjDVE2B5uU67jCB