app-patterns: promise_all_chains rejects with a resolution value at scale (Uncaught (in promise) 0) #7497

Split out of #7475, which turned out to be two unrelated defects. #7495 fixes the iterator-drain rooting bug that made object_deep_clone fail; this one is untouched by it.

Repro

PERRY_RUNTIME_DIR=$PWD/target/release ./target/release/perry \
  benchmarks/app-patterns/kernels/promise_all_chains.ts -o /tmp/p && /tmp/p

Node prints checksum: 2500050000.

Why this is a separate defect from #7475's rooting bug

#7495 roots the five live GC values js_iterator_to_array carried in bare Rust locals across an allocating .next(). That made object_deep_clone correct under both links. promise_all_chains is unchanged by it, in both configurations — which is the evidence that it is not the same family.

The PERRY_NO_AUTO_OPTIMIZE=1 message is the interesting one. Uncaught (in promise) 0 says a promise REJECTED with the value 0 — and 0 is unitOfWork(0)'s first await Promise.resolve(i) value, i.e. a resolution value arriving on the rejection path, not a rooting-shaped wild pointer.

Scale-dependent

The kernel is N_BATCHES = 1000, BATCH_SIZE = 50 — 50 000 three-deep await chains, drained 50 at a time through Promise.all. Reduced to N_BATCHES = 3, BATCH_SIZE = 5 it prints the correct checksum: 240. So it needs scale; a first look should establish whether the threshold is a count, a microtask-queue depth, or a collection.

Impact

This is the last blocker on the public benchmark artifact: run_public_baseline.sh completes all four legs and then refuses on "app-pattern component is incomplete or has a correctness failure" for this one kernel. It is also the single entry in the skip list of the new auto-opt-app-patterns gate (scripts/auto_opt_app_patterns.sh), and that list is rot-checked — a skip naming a kernel that no longer exists fails the script — so the line comes out with the fix.

The other eleven app-pattern kernels pass through the auto-optimize link on #7495's branch.