fix(editor): render NodeViewContent first so click hit-testing isn't offset (#146)

Three editable NodeViews rendered a contentEditable=false "chrome" element IN
FLOW BEFORE NodeViewContent. On macOS the browser's click hit-testing
(posAtCoords → caretRangeFromPoint) then misses the contentDOM and snaps the
caret to the previous node — the caret/selection lands a line (code block) or
several lines (footnotes, into the body) above where the user clicked.

Fix (the transclusion pattern / issue #146 plan): make the editable
NodeViewContent the FIRST child in the DOM and move the non-editable chrome
AFTER it, restoring its visual position with CSS:

- code-block-view: <pre><NodeViewContent/></pre> first; the language/copy menu
  follows and is lifted above via flex `order` (.codeBlock is now a flex column).
- footnotes-list-view: NodeViewContent first; the "Footnotes" heading follows and
  is lifted above via flex `order` (.list is a flex column; the separator border
  stays on the container).
- footnote-definition-view: NodeViewContent first; the "N." marker follows with
  `order:-1` to stay on the left; the ↩ back-link stays on the right.

Layout is visually unchanged. Verified in a real browser (Chromium): the
contentDOM is now the first child of every editable NodeView wrapper (no
contentEditable=false element precedes it), and the menu/heading/marker still
render in their original positions.

NOTE: the caret-offset itself is macOS-specific text hit-testing and does not
reproduce in headless Chromium/WebKit on Linux (verified extensively), so the
visible fix is best confirmed on macOS.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/client/src/features/editor/components/code-block/code-block.module.css

@@ -17,7 +17,14 @@
     justify-content: center;
 }
 
+/* #146: the menu now follows the <pre> in the DOM (so the editable contentDOM is
+   FIRST and click hit-testing is correct). Lift it back ABOVE the code visually
+   with flex `order` — the .codeBlock wrapper is a flex column (see code.css) —
+   so the menu still reads as a row above the code, exactly as before, without
+   sitting in-flow before the contentDOM. */
 .menuGroup {
+    order: -1;
+
     @media print {
         display: none;
     }