test(editor): guard #146 contentDOM-first invariant + fix code-block comment (PR #147 review)

Addresses the #147 review (Approve with comments):
- Add footnote-views.structure.test.tsx: a structural regression guard asserting
  the editable NodeViewContent is the FIRST child of FootnotesListView and
  FootnoteDefinitionView, with no contenteditable=false chrome before it. The
  whole #146 fix rests on this DOM-order invariant; the macOS caret symptom needs
  a real browser, but the order proxy is testable in jsdom. Stubs @tiptap/react
  so the views render as plain DOM — the test passes on the fixed order and fails
  on the pre-fix chrome-first order.
- Reword the code-block-view comment: it claimed a "top-right overlay (the
  transclusion pattern)", but the menu stays fully in flow as a full-width row
  lifted via flex `order: -1` (the .codeBlock wrapper is a flex column). No
  overlay/absolute positioning.

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

apps/client/src/features/editor/components/footnote/footnote-views.structure.test.tsx

@@ -0,0 +1,91 @@
+import { describe, it, expect, vi } from "vitest";
+import { render } from "@testing-library/react";
+
+/**
+ * Structural regression guard for #146 (PR #147).
+ *
+ * The caret/click-offset fix rests entirely on ONE invariant: in every editable
+ * footnote NodeView the editable `NodeViewContent` (contentDOM) must be the
+ * FIRST child of the wrapper, with no non-editable (`contenteditable="false"`)
+ * element before it. If a future edit reinserts chrome (separator, heading,
+ * marker, back-link) ahead of the content, the macOS hit-testing bug returns
+ * silently — and the symptom needs a real browser to see. This test pins the
+ * DOM ORDER (the proxy that IS the fix) in the existing jsdom harness.
+ *
+ * We stub `@tiptap/react` so the views render as plain DOM and we can inspect
+ * the child order our JSX produces — that order is exactly what regresses, and
+ * it does not depend on a live editor. The stubbed `NodeViewContent` carries the
+ * real `data-node-view-content` marker tiptap uses, so the assertion mirrors
+ * production. This test passes on the fixed order and FAILS on the pre-fix order
+ * (chrome-before-content).
+ */
+vi.mock("@tiptap/react", () => ({
+  NodeViewWrapper: ({ children, ...props }: any) => (
+    <div data-testid="nvw" {...props}>
+      {children}
+    </div>
+  ),
+  // Mirror the real contentDOM marker so the guard matches production output.
+  NodeViewContent: (props: any) => <div data-node-view-content="" {...props} />,
+}));
+
+vi.mock("react-i18next", () => ({
+  useTranslation: () => ({ t: (key: string) => key }),
+}));
+
+// footnote-definition-view reads a cached number from the numbering plugin;
+// stub it so we don't need a live ProseMirror state.
+vi.mock("@docmost/editor-ext", () => ({
+  getFootnoteNumber: () => 1,
+}));
+
+import FootnotesListView from "./footnotes-list-view";
+import FootnoteDefinitionView from "./footnote-definition-view";
+
+// Minimal NodeViewProps stub: definition view only touches node.attrs.id and
+// editor.state (the latter unused once getFootnoteNumber is mocked).
+const props = {
+  node: { attrs: { id: "fn-1" }, textContent: "" },
+  editor: { state: {}, isEditable: true, commands: {} },
+  getPos: () => 0,
+  updateAttributes: () => {},
+  deleteNode: () => {},
+} as any;
+
+const cases: Array<{ name: string; ui: React.ReactElement }> = [
+  { name: "FootnotesListView", ui: <FootnotesListView {...props} /> },
+  { name: "FootnoteDefinitionView", ui: <FootnoteDefinitionView {...props} /> },
+];
+
+describe("#146 footnote NodeView DOM-order invariant", () => {
+  it.each(cases)(
+    "$name renders contentDOM as the first child",
+    ({ ui }) => {
+      const { getByTestId } = render(ui);
+      const wrapper = getByTestId("nvw");
+
+      const firstEl = wrapper.firstElementChild;
+      expect(firstEl).not.toBeNull();
+      // The editable content must be physically first.
+      expect(firstEl?.hasAttribute("data-node-view-content")).toBe(true);
+    },
+  );
+
+  it.each(cases)(
+    "$name has no contentEditable=false chrome BEFORE the content",
+    ({ ui }) => {
+      const { getByTestId } = render(ui);
+      const wrapper = getByTestId("nvw");
+
+      const content = wrapper.querySelector("[data-node-view-content]")!;
+      const nonEditable = wrapper.querySelectorAll('[contenteditable="false"]');
+      expect(nonEditable.length).toBeGreaterThan(0); // chrome exists...
+
+      for (const el of Array.from(nonEditable)) {
+        // ...but every non-editable element must come AFTER the content node.
+        const pos = content.compareDocumentPosition(el);
+        expect(pos & Node.DOCUMENT_POSITION_FOLLOWING).toBeTruthy();
+      }
+    },
+  );
+});