maude: confluence / critical-pair checking (12 tests, 274 total)

lib/maude/confluence.sx — two-sided syntactic unification (occurs-checked) →
critical pairs from LHS overlaps → joinability via AC-canonical normal forms.
mau/confluent? / mau/non-joinable-pairs / mau/critical-pairs / mau/cp->str.
Catches f(a)=b,a=c (b <?> f(c)); peano/idempotent/AC confirmed confluent.
Syntactic overlaps (AC under-approximated, joinability uses canon). This is
the CID-stability oracle for the artdag optimiser.

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

lib/maude/conformance.conf

@@ -13,6 +13,7 @@ PRELOADS=(
   lib/maude/matching.sx
   lib/maude/conditional.sx
   lib/maude/fire.sx
+  lib/maude/confluence.sx
   lib/maude/rewrite.sx
   lib/maude/searchpath.sx
   lib/maude/strategy.sx
@@ -25,6 +26,7 @@ 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!)"
+  "confluence:lib/maude/tests/confluence.sx:(mau-confluence-tests-run!)"
   "conditional:lib/maude/tests/conditional.sx:(mau-conditional-tests-run!)"
   "owise:lib/maude/tests/owise.sx:(mau-owise-tests-run!)"
   "gather:lib/maude/tests/gather.sx:(mau-gather-tests-run!)"