Update vendor/compare_view submodule to v1.3.4

Was pinned at commit c49e17b (source: 6846d5d, "undo scaling", July
2022) - 59 commits behind compare_view's main. Missing since then:
drag-and-drop support, dynamic image updates (load_new_imgs), several
fixes, and version bumps v1.2.0 through v1.3.4.

Checked compatibility before bumping: template.html only calls
compare_view.load(image_urls, canvas_id, config), and both that
function's signature and the Config schema are unchanged between the
old and new build (the new version only adds optional params/exports).

Verified locally: compare() still renders correctly (canvas + controls,
zero console/page errors) against the updated bundle in a real venv
with the package installed editable.

Not releasing yet - pin update only, for review.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: kolibril13