persist: crash/restart recovery integration + migration notes — Phase 4 complete

recovery.sx: 6-test end-to-end crash/restart of an order ledger (log +
subscription kv read model + snapshot + compaction + invoice blob ref) on the
durable backend; everything survives a restart over the same disk + content
store, seq continues, two restarts converge. Migration notes (mem → durable
under a live subsystem) added to the plan. Roadmap done, 111/111.

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

lib/persist/scoreboard.json

@@ -9,9 +9,10 @@
     "snapshot": {"pass": 11, "fail": 0},
     "compaction": {"pass": 11, "fail": 0},
     "durable": {"pass": 15, "fail": 0},
-    "blob": {"pass": 14, "fail": 0}
+    "blob": {"pass": 14, "fail": 0},
+    "recovery": {"pass": 6, "fail": 0}
   },
-  "total_pass": 105,
+  "total_pass": 111,
   "total_fail": 0,
-  "total": 105
+  "total": 111
 }