F1: add code-block-view.test.tsx (mirrors the footnote structure harness) asserting
the language selector renders only when editor.isEditable, and the copy button is
present in both modes.
F2: remove the now-dead justify=flex-end on the absolutely-positioned menu Group.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The code-block control panel (language selector + copy) took a full row above
the code. Move both to an absolute overlay in the top-right corner and hide the
language selector until the block is hovered/focused; the copy button stays
always visible. In read-only the language selector isn't rendered at all. The
<pre> (editable contentDOM) stays FIRST in the DOM so click hit-testing (#146)
is not regressed; the panel leaves the flow via position:absolute.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>