lua-runtime: add math/string/table stdlib + delay/force (185/185 pass)

math: abs/ceil/floor/sqrt/sin/cos/tan/asin/acos/atan/exp/log/max/min/pi/huge
string: len/sub/upper/lower/rep/reverse/byte/char/find/match/gmatch/gsub
table: insert/remove/concat/sort
lua-force: force promises (delay thunk protocol)
Fix lua-len: replace has? (unavailable in sx_server) with nil-check.
Fix string.byte: use string->list to get char type, not nth on string.
Fix string.char: truncate float codes before integer->char.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/lua/test.sh

@@ -633,6 +633,116 @@ check 482 "while i<5 count"                 '5'
 check 483 "repeat until i>=3"               '3'
 check 484 "for 1..100 sum"                  '5050'
 
+# ── Phase 3: stdlib — math, string, table ──────────────────────────────────
+
+cat >> "$TMPFILE" << 'EPOCHS2'
+
+;; ── math library ───────────────────────────────────────────────
+(epoch 500)
+(eval "(lua-eval-ast \"return math.abs(-7)\")")
+(epoch 501)
+(eval "(lua-eval-ast \"return math.floor(3.9)\")")
+(epoch 502)
+(eval "(lua-eval-ast \"return math.ceil(3.1)\")")
+(epoch 503)
+(eval "(lua-eval-ast \"return math.sqrt(9)\")")
+(epoch 504)
+(eval "(lua-eval-ast \"return math.sin(0)\")")
+(epoch 505)
+(eval "(lua-eval-ast \"return math.cos(0)\")")
+(epoch 506)
+(eval "(lua-eval-ast \"return math.max(3, 7)\")")
+(epoch 507)
+(eval "(lua-eval-ast \"return math.min(3, 7)\")")
+(epoch 508)
+(eval "(lua-eval-ast \"return math.pi > 3\")")
+(epoch 509)
+(eval "(lua-eval-ast \"return math.huge > 0\")")
+
+;; ── string library ─────────────────────────────────────────────
+(epoch 520)
+(eval "(lua-eval-ast \"return string.len(\\\"hello\\\")\")")
+(epoch 521)
+(eval "(lua-eval-ast \"return string.upper(\\\"hello\\\")\")")
+(epoch 522)
+(eval "(lua-eval-ast \"return string.lower(\\\"WORLD\\\")\")")
+(epoch 523)
+(eval "(lua-eval-ast \"return string.sub(\\\"hello\\\", 2, 4)\")")
+(epoch 524)
+(eval "(lua-eval-ast \"return string.rep(\\\"ab\\\", 3)\")")
+(epoch 525)
+(eval "(lua-eval-ast \"return string.reverse(\\\"hello\\\")\")")
+(epoch 526)
+(eval "(lua-eval-ast \"return string.byte(\\\"A\\\")\")")
+(epoch 527)
+(eval "(lua-eval-ast \"return string.char(72, 105)\")")
+(epoch 528)
+(eval "(lua-eval-ast \"return string.find(\\\"hello\\\", \\\"ll\\\")\")")
+(epoch 529)
+(eval "(lua-eval-ast \"return string.match(\\\"hello\\\", \\\"ell\\\")\")")
+(epoch 530)
+(eval "(lua-eval-ast \"return string.gsub(\\\"hello\\\", \\\"l\\\", \\\"r\\\")\")")
+
+;; ── table library ──────────────────────────────────────────────
+(epoch 540)
+(eval "(lua-eval-ast \"local t = {10, 20, 30} t = table.insert(t, 40) return t[4]\")")
+(epoch 541)
+(eval "(lua-eval-ast \"local t = {10, 20, 30} t = table.remove(t) return t[3]\")")
+(epoch 542)
+(eval "(lua-eval-ast \"local t = {\\\"a\\\", \\\"b\\\", \\\"c\\\"} return table.concat(t, \\\",\\\")\")")
+(epoch 543)
+(eval "(lua-eval-ast \"local t = {3, 1, 2} t = table.sort(t) return t[1]\")")
+(epoch 544)
+(eval "(lua-eval-ast \"local t = {3, 1, 2} t = table.sort(t) return t[3]\")")
+
+;; ── delay / force ──────────────────────────────────────────────
+(epoch 550)
+(eval "(lua-force (delay (+ 10 5)))")
+(epoch 551)
+(eval "(lua-force 42)")
+
+EPOCHS2
+
+OUTPUT2=$(timeout 30 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
+OUTPUT="$OUTPUT
+$OUTPUT2"
+
+# math
+check 500 "math.abs(-7)"         '7'
+check 501 "math.floor(3.9)"      '3'
+check 502 "math.ceil(3.1)"       '4'
+check 503 "math.sqrt(9)"         '3'
+check 504 "math.sin(0)"          '0'
+check 505 "math.cos(0)"          '1'
+check 506 "math.max(3,7)"        '7'
+check 507 "math.min(3,7)"        '3'
+check 508 "math.pi > 3"          'true'
+check 509 "math.huge > 0"        'true'
+
+# string
+check 520 "string.len"           '5'
+check 521 "string.upper"         '"HELLO"'
+check 522 "string.lower"         '"world"'
+check 523 "string.sub(2,4)"      '"ell"'
+check 524 "string.rep(ab,3)"     '"ababab"'
+check 525 "string.reverse"       '"olleh"'
+check 526 "string.byte(A)"       '65'
+check 527 "string.char(72,105)"  '"Hi"'
+check 528 "string.find ll"       '3'
+check 529 "string.match ell"     '"ell"'
+check 530 "string.gsub l->r"     '"herro"'
+
+# table
+check 540 "table.insert"         '40'
+check 541 "table.remove"         'nil'
+check 542 "table.concat ,"       '"a,b,c"'
+check 543 "table.sort [1]"       '1'
+check 544 "table.sort [3]"       '3'
+
+# delay/force
+check 550 "lua-force delay"      '15'
+check 551 "lua-force non-promise" '42'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL Lua-on-SX tests passed"