Parent: #140 Profiles: #163, #164 Roadmap: #134
Implement Bun__attachAsyncStackFromPromise from the pinned upstream algorithm, including the runtime metadata it depends on.
Acceptance:
- Track pending Promise reaction links to suspended async-function/generator activations without retaining completed activations.
- Retain each suspension's exact function, script, source position/byte offset, async flag, and parent result-Promise link.
- Walk direct await and plain thenable-forwarding chains with the upstream 32-hop guard; stop at combinators, invalid links, settled promises, or the configured stack limit.
- Attach frames only to native Error instances that have neither an existing structured trace nor materialized error info; preserve user-provided/synchronous stacks.
- Respect selected-realm stackTraceLimit, including zero, and never replace an existing VM exception.
- Trace all live links precisely through GC and clear them on settlement/completion so no Promise/generator graph leaks.
- Cover nested awaits, rejection from native/event-loop code, sibling realms, empty/settled/non-Promise/null inputs, chain/hop/limit boundaries, materialized stacks, existing stacks, and GC.
- Add the export to both inventories, the compiled fixture, API/ABI docs, README evidence, and publish zero-unclassified audit counts.
This remains separate from #253: that issue registers native Promise callbacks; this one reconstructs structured async stack metadata.