content: nested-tree CvRDT (crdt-tree.sx) + 17 convergence tests (727/727)

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

lib/content/scoreboard.json

@@ -34,13 +34,14 @@
     "store": {"pass": 29, "fail": 0},
     "snapshot": {"pass": 20, "fail": 0},
     "crdt": {"pass": 34, "fail": 0},
+    "crdt-tree": {"pass": 17, "fail": 0},
     "crdt-store": {"pass": 14, "fail": 0},
     "sync": {"pass": 14, "fail": 0},
     "md-import": {"pass": 38, "fail": 0},
     "md-doc": {"pass": 12, "fail": 0},
     "fed": {"pass": 20, "fail": 0}
   },
-  "total_pass": 710,
+  "total_pass": 727,
   "total_fail": 0,
-  "total": 710
+  "total": 727
 }