maude: artdag-on-sx fit prototype — optimise passes as equations (8 tests, 262 total)

lib/maude/tests/effects.sx — proves artdag's effect-pipeline optimisations
(fusion, no-op/dead-op elim, identity elim, CSE/idempotent dedup) are
equational rewriting: the optimised pipeline is the normal form, confluence
gives a stable content id. The 'second consumer' spike for a maude-driven
optimiser in lib/artdag. Surfaced faithfulness note: id: affects matching/canon
not auto-reduction.

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

lib/maude/scoreboard.json

@@ -1,8 +1,8 @@
 {
   "lang": "maude",
-  "total_passed": 254,
+  "total_passed": 262,
   "total_failed": 0,
-  "total": 254,
+  "total": 262,
   "suites": [
     {"name":"parse","passed":65,"failed":0,"total":65},
     {"name":"reduce","passed":26,"failed":0,"total":26},
@@ -16,7 +16,8 @@
     {"name":"strategy","passed":19,"failed":0,"total":19},
     {"name":"meta","passed":18,"failed":0,"total":18},
     {"name":"pretty","passed":11,"failed":0,"total":11},
-    {"name":"run","passed":10,"failed":0,"total":10}
+    {"name":"run","passed":10,"failed":0,"total":10},
+    {"name":"effects","passed":8,"failed":0,"total":8}
   ],
-  "generated": "2026-06-07T15:51:45+00:00"
+  "generated": "2026-06-07T19:38:27+00:00"
 }