Add evidence-backed pthread utility helpers

[millesant]

Closes #43

Summary

• add bounded logical pthread_getschedparam, pthread_setschedparam, and pthread_setname_np support for the ARM32 VLC imports actually present in the supplied APK
• keep scheduler state synthetic (SCHED_OTHER/0) and thread names bounded/logical; never mutate host pthread state
• extend the ARM32 libc shim fixture, lifecycle integration, focused unit regressions, workflow evidence gates, contracts, architecture, and reproducible import evidence
• correct the supplied libemu32.so evidence: it is AArch64, so its semaphore/attr-scheduling imports do not expand the AArch32 surface

Validation

• static exact diff review: 11 intended files, one commit, branch ahead 1 / behind 0
• local build/tests: NOT RUN in this environment
• GitHub Actions: pending exact-head snapshot