- Detect HTTP/HTTPS links in follow_selected_link and dispatch to navigate_to_remote()
- Add navigate_to_remote() method with whitelist check, fetch, render, history push, and error screens
- Handle DomainNotAllowed/FetchError/NotMarkdown with BBS-themed error screens (no history push)
- Update navigate_back/forward to re-fetch remote URLs from history (consistent with disk-reload pattern)
- Update handle_resize() to pass None vault_path for remote pages
- Skip live-reload for remote pages in reload_current_document()
- Clear current_url when navigating to local pages in navigate_to()
- Style HTTP/HTTPS links in LightMagenta to visually distinguish from local LightCyan links