Kiwix-serve: external link blocker does not respect the `target` attribute

[benoit74]

See e.g. https://dev.library.kiwix.org/viewer#libretexts.org_en_workforce_2024-12/index.html (or any other libretexts ZIM in dev library ... or prod soon hopefully).

When you click on the blue globe in the top right corner, the target is _blank but the external link blocker opens in same tab.

[Optimus-NP]

Thanks to @veloman-yunkan

✅ This issue has been resolved by PR #1176.

The problem was that the external link blocker was not respecting the _blank target, causing external links (like the blue globe icon in the top right) to open in the same tab instead of a new one.

Fix Details:

• The fix ensures that links explicitly set to open in _blank are properly handled.
• Now, clicking external links opens them in a new tab as expected.

[kelson42]

@Optimus-NP Thx, we will check and close