add Lua sandbox with timer system (milestones 1-5 complete)

sandbox-test/scripts/test_memory_limit.lua

@@ -0,0 +1,20 @@
+-- This script intentionally tries to exhaust memory
+-- When run with a 512KB limit, it should fail before completing
+
+local t = {}
+local i = 0
+
+while true do
+    i = i + 1
+    -- Each string is 100KB
+    t[i] = string.rep("x", 100000)
+
+    -- Safety check - if we get past 100 iterations with 512KB limit,
+    -- something is wrong
+    if i > 100 then
+        error("FAIL: Should have hit memory limit by now (allocated ~10MB)")
+    end
+end
+
+-- Should never reach here
+error("FAIL: Memory limit not enforced")