add JSON and crypto APIs with sandbox protection (milestone 6 complete)

src/main/cpp/sandbox/json_api.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <string>
+#include <cstddef>
+
+struct lua_State;
+
+namespace mosis {
+
+// Configuration limits for JSON operations
+struct JsonLimits {
+    int max_depth = 32;                          // Maximum nesting depth
+    size_t max_string_length = 1 * 1024 * 1024;  // 1 MB per string
+    size_t max_output_size = 10 * 1024 * 1024;   // 10 MB total output
+    size_t max_array_size = 100000;              // Max elements in array
+    size_t max_object_size = 10000;              // Max keys in object
+};
+
+// Register json.encode() and json.decode() as globals
+void RegisterJsonAPI(lua_State* L, const JsonLimits& limits = JsonLimits{});
+
+} // namespace mosis