Chat UI Tests was failing in CI with "<html> intercepts pointer events"
on the New Chat sidebar click. Root cause: after the theme toggle's
animated reveal, Chromium's view-transition state can leave the html
element reported as the topmost click target for a beat -- even after
the documentElement classList has settled. The previous CSS-only
neutraliser (animation: none + pointer-events: auto) wasn't enough
once the runtime captured the html.
Two-pronged fix in both playwright_chat_ui.py and playwright_extra_ui.py:
1. Monkey-patch document.startViewTransition in add_init_script so
the callback runs synchronously, no animation pipeline runs, and
the html is never captured. This is the only way to fully
neutralise the transition without disabling the feature in the
app code.
2. Use force=True + a 5s timeout in click_nav() (sidebar nav
clicks). The element IS visible + enabled; force=True bypasses
Playwright's actionability check belt-and-suspenders if the
monkey-patch ever misses an edge case.
Also broadened the CSS pseudo-element list (added ::view-transition,
-group, -image-pair) to display:none, so even if startViewTransition
is somehow re-attached, the captured pseudos can't paint over the page.