maude: Phase 1 parser — fmod/mod modules, signatures, mixfix terms (65 tests)

Term representation (lib/maude/term.sx) plus a module parser
(lib/maude/parser.sx) consuming lib/guest/lex + pratt:

- whitespace+bracket tokenizer (--- / *** comments)
- mixfix classification (split op names on _): infix/prefix/postfix/const
- precedence-climbing term parser over a pratt table built from op decls
- fmod/mod ... endfm/endm with sort/subsort/op/var/eq/ceq/rl/crl
- transitive subsort hierarchy + operator overloading queries

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

plans/maude-on-sx.md

@@ -62,10 +62,10 @@ The novel substrate stress: equational matching. Pattern `X + Y` against `1 + 2
 ## Roadmap
 
 ### Phase 1 — Parser + signatures
-- [ ] Parser for `fmod` / `endfm` syntax, sort declarations, op declarations, equations.
-- [ ] Sort hierarchy with subsort relations.
-- [ ] Operator overloading by arity + sort.
-- [ ] Tests: parse classic examples (peano nat, list of naturals).
+- [x] Parser for `fmod` / `endfm` syntax, sort declarations, op declarations, equations.
+- [x] Sort hierarchy with subsort relations.
+- [x] Operator overloading by arity + sort.
+- [x] Tests: parse classic examples (peano nat, list of naturals).
 
 ### Phase 2 — Syntactic equational reduction
 - [ ] Apply equations left-to-right until no equation matches.
@@ -125,7 +125,22 @@ The novel substrate stress: equational matching. Pattern `X + Y` against `1 + 2
 - Pure language (Albrecht Gräf): https://agraef.github.io/pure-lang/ — practical functional rewriting.
 
 ## Progress log
-_(awaiting Phase 1 — depends on substrate matching maturity from lib/guest/core/match.sx)_
+
+- **Phase 1 (parser + signatures) — DONE, 65/65.** `lib/maude/term.sx` (term
+  repr: var/app dicts, equality, vars, `term->str`) + `lib/maude/parser.sx`
+  (whitespace+bracket tokenizer with `---`/`***` comments; mixfix
+  classification by splitting op names on `_`; precedence-climbing term parser
+  over a pratt table built from op decls; `fmod`/`mod` modules with
+  sorts/subsorts/ops/vars/eqs/rules). Consumes `lib/guest/lex.sx` (ws classes)
+  and `lib/guest/pratt.sx` (op-table lookup). Verified on Peano (`s X + Y`
+  parses `_+_(s_(X), Y)` — prefix binds tighter than infix) and NatList
+  (transitive subsorts NzNat<Nat<List; `_;_` overloaded; `id: nil` / `prec`
+  attrs). ceq/rl/crl parsed structurally (cond split on `if`, label in `[..]`).
+  Suite + conformance driver wired (`lib/maude/conformance.{conf,sh}`, MODE=dict).
+  - Notes for next phases: terms are `{:t :app :op N :args (...)}` /
+    `{:t :var :name N :sort S}`; module carries a `:grammar` so
+    `mau/parse-term-in` can parse term strings against its op table. Overloading
+    is recorded but NOT resolved at parse time (resolve at reduce time).
 
 ## Blockers
-_(speculative — equational matching is algorithmically heavy and may surface JIT issues)_
+_(none)_