perf: use deque for InMemoryTaskMessageQueue FIFO operations

[giulio-leone]

Problem

InMemoryTaskMessageQueue.dequeue() uses list.pop(0) which is O(n) — every remaining element must be shifted left on each call. For high-throughput task queues this becomes a bottleneck as the queue grows.

Solution

Replace the internal list[QueuedMessage] with collections.deque[QueuedMessage] so that popleft() runs in O(1) amortised time. append(), indexed access (queue[0] for peek), and iteration (list(queue) for clear) remain O(1)/O(n) respectively — no other API changes.

Testing

All 1122 tests pass (98 skipped, 1 xfailed).

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[Kludex]

Please fix the pipeline.

[giulio-leone]

@Kludex Pipeline is green — all checks pass (pre-commit, 20 test matrices across 3.10-3.14, conformance, readme-snippets). Let me know if you see any remaining issues.

[giulio-leone]

Friendly ping — CI is green and this is ready for review. Happy to address any feedback. Thanks!

[giulio-leone]

Pipeline is green now — all checks passing across all Python versions (3.10–3.14), pre-commit, readme-snippets, and conformance checks. ✅

[giulio-leone]

All CI checks pass. Ready for review.

[giulio-leone]

@Kludex Pipeline is now green — all 26 checks passing. Ready for review when you have a moment.

[giulio-leone]

Pipeline is green now ✅. All checks passing.