Renew approved-contrast selectors for the code block redesign

Same reviewed findings, differently-shaped axe selectors: code.json's
selector attribute changed from [role="group"] to [data-view="file"]
because the redesign adds that attribute to the same code-preview div.
Also drops one narrow-only entry (the "12" digit contrast finding,
still present at wide) that no longer surfaces as a separate node,
most likely merged into an adjacent span by the new header's
line-wrapping at that width. chat.json's three entries are the same
approved chat-timestamp/queued-status finding with two Tailwind
classes reordered in axe's generated selector string; chat.tsx itself
is untouched by this PR.

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