top-level await (#261)

* update based on the changes in the main (minus ts executor)

* small type fix

* fix some integration tests

* Update packages/sandbox-container/tests/runtime/thenable.test.ts

Co-authored-by: Naresh <[email protected]>

* add variable hoisting for const, let, and var; timeout handling for async; update tests

* small nits to tests and some checks

---------

Co-authored-by: Naresh <[email protected]>

Author: whoiskatrin

.changeset/top-level-await.md

@@ -0,0 +1,15 @@
+---
+'@cloudflare/sandbox': patch
+---
+
+Add top-level await support for JavaScript code execution
+
+JavaScript code can now use `await` at the top level without wrapping in an async IIFE. Variables declared with `const`, `let`, or `var` persist across executions, enabling multi-step workflows like:
+
+```javascript
+// Execution 1
+const data = await fetch('https://api.example.com').then((r) => r.json());
+
+// Execution 2
+console.log(data); // Works - data persists
+```