test(mcp): align nested-list goldens with the #351 loose-container converter fix

The #351 converter fix (79a461f7) made multi-block list items emit a blank-line
separator between block children (loose list) to stop silent content merging on
re-parse. The prosemirror-markdown goldens were updated in that PR, but the two
mcp unit tests asserting the old tight output were missed — packages/mcp
re-exports the shared converter, so they broke the develop CI run (test job,
`pnpm -r test`, 2/480 failures).

- expect "- Parent\n\n  - A..." instead of "- Parent\n  - A..."
- expect "1. Parent\n\n   - Child" instead of "1. Parent\n   - Child"

Full mcp suite: 480/480 green; editor-ext / prosemirror-markdown / client /
git-sync suites green as well.

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

packages/mcp/test/unit/markdown-converter.test.mjs

@@ -25,9 +25,11 @@ test("nested bulletList with 3 children keeps all children indented under the pa
     ),
   );
 
+  // Block children of a list item are blank-line separated (loose list) since
+  // the #351 converter fix; the sublist stays nested at the 2-col marker column.
   assert.equal(
     convertProseMirrorToMarkdown(input),
-    "- Parent\n  - A\n  - B\n  - C",
+    "- Parent\n\n  - A\n  - B\n  - C",
   );
 });
 
@@ -41,9 +43,10 @@ test("nested list under an ordered item indents 3 spaces", () => {
     ),
   );
 
+  // Blank-line separated block children (loose list) per the #351 converter fix.
   assert.equal(
     convertProseMirrorToMarkdown(input),
-    "1. Parent\n   - Child",
+    "1. Parent\n\n   - Child",
   );
 });