Clean-up certain components before htmx navigation save

[cotti]

Fixes #2440

Summary

This pull request adds a cleanup routine to ensure that certain web components and portal containers are properly reset before htmx saves the page state to its history cache in localStorage. This prevents issues with stale or orphaned DOM elements during client-side navigation.

Frontend cleanup improvements:

• Added an event listener for htmx:beforeHistorySave in main.ts to clear the inner HTML of applies-to-popover, version-dropdown, and search-or-ask-ai web components before htmx caches the page.
• Removed orphaned EUI portal containers (elements with data-euiportal="true") before htmx history caching to prevent DOM clutter during navigation.

[Mpdreamz]

LGTM for a hot patch, we should tackle this more generically near term.

Either through hx-history="false"

htmx.config.historyCacheSize = 0;

This caching behaviour will go away with htmx 4.0 anyhow

https://htmx.org/essays/the-fetchening/#htmx-4-the-fetch-ening

[cotti]

LGTM for a hot patch, we should tackle this more generically near term.

Either through hx-history="false"

htmx.config.historyCacheSize = 0;

This caching behaviour will go away with htmx 4.0 anyhow

https://htmx.org/essays/the-fetchening/#htmx-4-the-fetch-ening

Ah, hx-history-elt would probably do it on a per-element basis.