Support async v5 solver steps in TscircuitAutorouter loop

[seveibar]

Motivation

• The v5 autorouter pipeline performs async work and exposes stepAsync(), and the existing synchronous loop could exhaust iterations while awaiting external promises.
• The autorouter loop needs to await async solver steps when available to avoid spinning step() and hitting MAX_ITERATIONS limits.

Description

• Added a stepSolver() helper that awaits solver.stepAsync() when present and falls back to solver.step() for synchronous solvers in lib/utils/autorouting/CapacityMeshAutorouter.ts.
• Converted the internal cycle runner runCycleAndQueueNextCycle() to an async function and awaited stepSolver() inside the time-sliced loop, preserving progress events and scheduling behavior.
• Ensured start() still has a void return and launches the async cycle runner without changing the public API surface.
• Added a regression test tests/features/autorouter-version-v5-async-step.test.ts that monkey-patches the v5 solver with a fake async implementation and verifies stepAsync() is used (and step() is not).

Testing

• Ran bun test tests/features/autorouter-version-v5-async-step.test.ts, and the test passed (1 pass, 0 fail).
• Ran typecheck with bunx tsc --noEmit, which completed with no errors.
• Ran formatter with bun run format, which completed successfully.

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Codex Task

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Project	Deployment	Actions	Updated (UTC)
tscircuit-core-benchmarks	Ready	Preview, Comment	Apr 5, 2026 4:45am

[github-actions]

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[github-actions]

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