prolog: operator-table parser + < > =< >= built-ins, 19 tests

plans/prolog-on-sx.md

@@ -65,7 +65,7 @@ Representation choices (finalise in phase 1, document here):
 - [x] Target: all 5 classic programs passing — append (6) + reverse (6) + member (7) + nqueens (6) + family (10) = 35 program tests, all green. Phase 3 architecturally complete bar the conformance harness/scoreboard.
 
 ### Phase 4 — operator table + more built-ins (next run)
-- [ ] Operator table parsing (prefix/infix/postfix, precedence, assoc)
+- [x] Operator table parsing (prefix/infix/postfix, precedence, assoc) — `pl-op-table` (15 entries: `, ; -> = \= is < > =< >= + - * / mod`); precedence-climbing parser via `pp-parse-primary` + `pp-parse-term-prec` + `pp-parse-op-rhs`. Parens override precedence. Args inside compounds parsed at 999 so `,` stays as separator. xfx/xfy/yfx supported; prefix/postfix deferred (so `-5` still tokenises as bare atom + num as before). Comparison built-ins `</2 >/2 =</2 >=/2` added. New `tests/operators.sx` 19 tests cover assoc/precedence/parens + solver via infix.
 - [ ] `assert/1`, `asserta/1`, `assertz/1`, `retract/1`
 - [ ] `findall/3`, `bagof/3`, `setof/3`
 - [ ] `copy_term/2`, `functor/3`, `arg/3`, `=../2`
@@ -88,6 +88,7 @@ Representation choices (finalise in phase 1, document here):
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-25 — Phase 4 starts: operator-table parsing. Parser rewrite uses precedence climbing (xfx/xfy/yfx); 15-op table covers control (`, ; ->`), comparison (`= \\= is < > =< >=`), arithmetic (`+ - * / mod`). Parens override. Backwards-compatible: prefix-syntax compounds (`=(X, Y)`, `+(2, 3)`) still parse as before; existing 183 tests untouched. Added comparison built-ins `</2 >/2 =</2 >=/2` to runtime (eval both sides, compare). New `tests/operators.sx` 19 tests; conformance script gained an operators row. Total **202** (+19). Prefix/postfix deferred — `-5` keeps old bare-atom semantics.
 - 2026-04-25 — Conformance harness landed. `lib/prolog/conformance.sh` runs all 9 suites in one sx_server epoch, parses the `{:failed/:passed/:total/:failures}` summary lines, and writes `scoreboard.json` + `scoreboard.md`. `SX_SERVER` env var overrides the binary path; default points at the main-repo build. Phase 3 fully complete: 183 / 183 passing across parse/unify/clausedb/solve/append/reverse/member/nqueens/family.
 - 2026-04-25 — `family.pl` fifth classic program — completes the 5-program target. 5-fact pedigree + male/female + derived father/mother/ancestor/sibling. 10 tests cover fact lookup + count, transitive ancestor through 3 generations, descendant counting (5), gender-restricted derivations, sibling via shared parent guarded by `\=`. Total 183 (+10). All 5 classic programs ticked; Phase 3 needs only conformance harness + scoreboard left.
 - 2026-04-25 — `nqueens.pl` fourth classic program. Permute-and-test variant exercises every Phase-3 feature: lists with `[H|T]` cons sugar, multi-clause backtracking, recursive `permute`/`select`/`safe`/`no_attack`, `is/2` arithmetic on diagonals, `\=/2` for diagonal-conflict check. 6 tests at N ∈ {1,2,3,4,5} with expected counts {1,0,0,2,10} + first-solution `[2,4,1,3]`. N=5 takes ~30s (120 perms × safe-check); N=8 omitted as it would be ~thousands of seconds. Total 173 (+6).