content: relative block reorder (move.sx) + 11 tests (668/668)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/content/scoreboard.json

@@ -12,6 +12,7 @@
     "section": {"pass": 25, "fail": 0},
     "compose": {"pass": 17, "fail": 0},
     "tree-edit": {"pass": 17, "fail": 0},
+    "move": {"pass": 11, "fail": 0},
     "clone": {"pass": 10, "fail": 0},
     "query": {"pass": 13, "fail": 0},
     "toc": {"pass": 8, "fail": 0},
@@ -36,7 +37,7 @@
     "md-doc": {"pass": 12, "fail": 0},
     "fed": {"pass": 20, "fail": 0}
   },
-  "total_pass": 657,
+  "total_pass": 668,
   "total_fail": 0,
-  "total": 657
+  "total": 668
 }