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/conformance.conf

@@ -35,4 +35,5 @@ SUITES=(
   "meta:lib/maude/tests/meta.sx:(mau-meta-tests-run!)"
   "pretty:lib/maude/tests/pretty.sx:(mau-pretty-tests-run!)"
   "run:lib/maude/tests/run.sx:(mau-run-tests-run!)"
+  "effects:lib/maude/tests/effects.sx:(mau-effects-tests-run!)"
 )