lua: math library (abs/trig/log/pow/min/max/fmod/modf/random/...) +17 tests

plans/lua-on-sx.md

@@ -69,7 +69,7 @@ Each item: implement → tests → tick box → update progress log.
 
 ### Phase 6 — standard library
 - [x] `string` — `format`, `sub`, `find`, `match`, `gmatch`, `gsub`, `len`, `rep`, `upper`, `lower`, `byte`, `char`
-- [ ] `math` — full surface
+- [x] `math` — full surface
 - [ ] `table` — `insert`, `remove`, `concat`, `sort`, `unpack`
 - [ ] `io` — minimal stub (read/write to SX IO surface)
 - [ ] `os` — time/date subset
@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-24: lua: `math` lib — pi/huge + abs/ceil/floor/sqrt/exp/log/log10/pow/trig (sin/cos/tan/asin/acos/atan/atan2)/deg/rad/min/max (&rest)/fmod/modf/random (0/1/2 arg)/randomseed. Most ops delegate to SX primitives; log w/ base via change-of-base. 309 tests.
 - 2026-04-24: lua: `string` lib — len/upper/lower/rep/sub (1-idx + neg)/byte/char/find/match/gmatch/gsub/format. Patterns are literal-only (no `%d`/etc.); format is `%s`/`%d`/`%f`/`%%` only. `string.char` uses printable-ASCII lookup + tab/nl/cr. 292 tests.
 - 2026-04-24: lua: phase 5 — coroutines (create/resume/yield/status/wrap) via `call/cc` (perform/cek-resume not exposed to SX userland). Handles multi-yield + final return + arg passthrough. Fix: body's final return must jump via `caller-k` to the **current** resume's caller, not unwind through the stale first-call continuation. 273 tests.
 - 2026-04-24: lua: generic `for … in …` — parser split (`=` → num, else `in`), new `lua-for-in` node, transpile to `let`-bound `f,s,var` + recursive `__for_loop`. Added `ipairs`/`pairs`/`next`/`lua-arg` globals. Lua fns now arity-tolerant (`&rest __args` + indexed bind) — needed because generic for always calls iter with 2 args. Noted early-return-in-nested-block as pre-existing limitation. 265 tests.