Gap: await using (Symbol.asyncDispose / ES2024 explicit resource management) #154

Summary

test-files/test_gap_async_advanced.ts (line 180-201) exercises await using with [Symbol.asyncDispose]() — the ES2024 explicit-resource-management proposal. Perry silently accepts the syntax but never runs the dispose hook.

Repro

async function test() {
  const disposed: string[] = [];
  class AsyncResource {
    name: string;
    constructor(name: string) { this.name = name; }
    async [Symbol.asyncDispose](): Promise<void> {
      await new Promise<void>((r) => setTimeout(r, 1));
      disposed.push(this.name);
    }
  }
  {
    await using r1 = new AsyncResource("res1");
    await using r2 = new AsyncResource("res2");
  }
  console.log(disposed.join(",")); // expected "res2,res1"
}

Actual vs Expected

• Perry: "" (dispose never ran)
• Node: "res2,res1" (disposed in reverse declaration order)

Scope

• Parse / lower await using and using binding forms
• Attach an implicit dispose queue per block scope; register each binding's [Symbol.asyncDispose]() on creation
• On block exit (success OR exception), await each registered disposer in reverse order, then re-throw any exception with SuppressedError chaining
• Synchronous using dispatches to [Symbol.dispose](); async dispatches to [Symbol.asyncDispose]()

Impact

One of six currently-failing gap tests (post v0.5.173, baseline 22/28 passing). Only this feature blocks test_gap_async_advanced from passing — everything else in that file works.