maude: program runner — module + reduce/rewrite commands (6 tests, 213 total)

lib/maude/run.sx — mau/run-program / mau/run parse a module plus trailing
reduce/red/rewrite/rew commands (with optional 'in MOD :' qualifier) and
execute them, rendering results in mixfix surface syntax. An idiomatic
.maude file now runs end-to-end.

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

plans/maude-on-sx.md

@@ -105,6 +105,10 @@ The novel substrate stress: equational matching. Pattern `X + Y` against `1 + 2
 - [x] Mixfix surface-syntax printer (`lib/maude/pretty.sx`) — `mau/term->maude`
   renders the internal prefix form back as Maude mixfix (`((s X) + 0)`),
   driven by op forms; `mau/red->maude` / `mau/rew->maude`. 11 tests.
+- [x] Program runner (`lib/maude/run.sx`) — `mau/run-program` / `mau/run` parse
+  a module plus trailing `reduce`/`red`/`rewrite`/`rew TERM .` commands
+  (`... in MOD : TERM` qualifier accepted) and execute them, rendering results
+  in surface syntax. Runs an idiomatic `.maude` file end-to-end. 6 tests.
 
 ### Phase 8 — Propose `lib/guest/rewriting/`
 - [ ] Extract equational matching engine (the most reusable piece).