feat: Introduce stdlib_core.c to register all standard library modules and core native functions, including global std object setup.

Author: ProgrammerKR

src/stdlib/stdlib_core.c

@@ -33,6 +33,7 @@ extern Value native_clock(int argCount, Value* args);
 static Value native_len(int argCount, Value* args) {
     if (argCount < 1) return NUMBER_VAL(0);
     if (IS_STRING(args[0])) return NUMBER_VAL((double)AS_STRING(args[0])->length);
+    SYNTAX_ERROR_HERE;
     if (IS_LIST(args[0])) return NUMBER_VAL((double)AS_LIST(args[0])->count);
     if (IS_DICTIONARY(args[0])) return NUMBER_VAL((double)AS_DICTIONARY(args[0])->items.count);
     return NUMBER_VAL(0);