commerce: reconciliation queries + federated-catalog stub (32 tests) — Phase 4 done

recon.sx — reconciliation as relational queries over the ledger: per-order
summary tuples + recon-statuso/neto/mismatcho miniKanren relations, so
overpaid/underpaid/settled and "settled to net N" are backward run* queries.
Tests cover double-charge guard, partial refund, webhook replay.

federation.sx (out-of-scope stub) — a federated catalog is the union of each
instance's product facts, so the same relations query cross-instance
(instances-with-sku, sku-offers, cheapest-offer). In-process mock, no network.

Completes the commerce-on-sx roadmap (Phases 1-4). Total 185/185 across 11 suites.

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

lib/commerce/scoreboard.json

@@ -8,9 +8,11 @@
     "stack": {"pass": 16, "fail": 0},
     "quote": {"pass": 13, "fail": 0},
     "ledger": {"pass": 20, "fail": 0},
-    "order": {"pass": 21, "fail": 0}
+    "order": {"pass": 21, "fail": 0},
+    "recon": {"pass": 20, "fail": 0},
+    "federation": {"pass": 12, "fail": 0}
   },
-  "total_pass": 153,
+  "total_pass": 185,
   "total_fail": 0,
-  "total": 153
+  "total": 185
 }