lua: math fns type-check args (math.sin() now errors instead of returning 0)

plans/lua-on-sx.md

@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-25: lua: scoreboard iteration — math fns now error on bad/missing args (was silently returning 0). New `lua-math-num "name" x` validator wraps `abs`/`ceil`/`floor`/`sqrt`/`exp`/`sin`/`cos`/`tan`/`asin`/`acos`/`atan`/`atan2`/`pow`. errors.lua moves past assert #4 (`pcall(math.sin)` now returns false+err as expected).
 - 2026-04-24: lua: scoreboard iteration — **pattern character sets** `[...]` and `[^...]`. New `lua-pat-set-end`/`lua-pat-set-match` helpers handle ranges (`[a-z]`), classes inside sets (`[%d%a]`), negation (`[^abc]`), and `[]...]`/`[^]...]` (literal `]` as first char). Asserts 6→4, but timeouts 3→7 — many tests now reach loop-heavy code. 387/387 green (+3 charset tests).
 - 2026-04-24: lua: scoreboard iteration — `tonumber(s, base)` for bases 2-36. Validates digit ranges per base, supports leading `+`/`-`, trims whitespace. `math.lua` past assert #21. Asserts 8→6, timeouts 3→4. 384/384 green.
 - 2026-04-24: lua: scoreboard iteration — added `lua-unwrap-final-return` (post-processor that rewrites top-level `(raise (list 'lua-ret V))` → `V` so top-level defines leak to SX top and loadstring closures can see them). Tried dropping the function-guard at top level, but too many tests use `if x then return 0 else return err end` at chunk tail, whose returns aren't at the *statement-list* tail — guard still needed. Kept guard + unwrap-as-no-op. Scoreboard unchanged.