Stabilize shared Voice verification gates

[MarcusJRLee]

Summary

• seal simulated crash recovery setup before moving its audio artifact
• run the mandatory 10,000-transition HID soak in an isolated test process without changing any percentile or maximum threshold
• serialize the two real AVFAudio exception-boundary tests

Verification

• complete host corpus: 480 tests / 72 suites passed (HID soak skipped only in the shared process)
• isolated HID soak: 10,000 ordered transitions; p50 0.011 ms, p95 0.017 ms, p99 0.025 ms, max 0.115 ms
• recovery fixture and strict Swift/shell formatting checks passed

No release, version, tag, or main changes.

[MarcusJRLee]

Integrated into dev through rebase-merged rollup PR #34. This intermediate PR remains preserved as the focused review record for its original slice.