maude: Phase 3 — equational matching modulo assoc/comm/id (28 tests, 119 total)

The chisel. lib/maude/matching.sx: multi-valued matcher mau/mm returning
ALL substitutions, dispatching on op theory (free/comm/assoc/AC). Identity
lets variables grab empty blocks. AC-canonical form (mau/canon) powers
ac-equal? and deterministic printout. AC rewriting extends f-AC equations
with rest vars so a rule fires on any sub-multiset/subword; mau/first-change
only commits rewrites that change the canonical form (idempotency/identity
terminate). Verified on multiset rewriting, set theory, group equations.

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

lib/maude/conformance.conf

@@ -9,9 +9,11 @@ PRELOADS=(
   lib/maude/term.sx
   lib/maude/parser.sx
   lib/maude/reduce.sx
+  lib/maude/matching.sx
 )
 
 SUITES=(
   "parse:lib/maude/tests/parse.sx:(mau-parse-tests-run!)"
   "reduce:lib/maude/tests/reduce.sx:(mau-reduce-tests-run!)"
+  "matching:lib/maude/tests/matching.sx:(mau-matching-tests-run!)"
 )