feat: arbitrary-precision BigInt via num-bigint (literals, arithmetic, toString, asIntN/asUintN)

crates/oxide_bytecode/Cargo.toml

@@ -8,3 +8,4 @@ description = "OxideJS - Shared bytecode protocol and compiled module ABI"
 
 [dependencies]
 oxide_log = { path = "../oxide_log" }
+num-bigint = "0.4"

crates/oxide_bytecode/src/module.rs

@@ -16,7 +16,7 @@ use crate::opcode::{self, OpCode};
 pub enum Constant {
     Number(f64),
     Int(i32),
-    BigInt(i128),
+    BigInt(num_bigint::BigInt),
     String(String),
     Boolean(bool),
     Null,