Add content-hash or version parameter to HTML resources for cache busting

## Description

HTML resources (scripts, stylesheets, etc.) are currently served without a content-hash or version query parameter. This can lead to stale cached assets being served by the browser after updates.

Resources should include either:
- A content-hash in the filename (e.g. `app.a1b2c3.js`) or as a query param (e.g. `app.js?v=a1b2c3`)
- A version parameter that changes on each build

This ensures browsers always fetch the latest version after a deployment, avoiding hard-to-debug caching issues.

## Action Items

- Review which HTML-served resources lack cache-busting identifiers
- Add content-hash or version params where needed

---
Requested by Pablo.dcl.eth via Slack