test(mcp): add workspace to write_note expected signature contract

The signature contract test pins exact tool parameters; update it for
the new workspace parameter.

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Drew Cain <groksrc@gmail.com>

tests/mcp/test_tool_contracts.py

@@ -109,6 +109,7 @@ EXPECTED_TOOL_SIGNATURES: dict[str, list[str]] = {
         "content",
         "directory",
         "project",
+        "workspace",
         "project_id",
         "tags",
         "note_type",