Pin runsc fix for checkpoint restore compaction stalls
VoxCPM2 checkpoints intermittently spent tens of seconds inside runsc restore even when the image and checkpoint were already local. Pin the exact node-tested runsc hotfix from beam-cloud/gvisor#3: honor the existing host huge-page policy to avoid synchronous compaction, and reduce shared-memory contention between checkpoint readers.
The artifact preserves the deployed checkpoint compatibility version (ebbaed3f9dd5). Serialized state is unchanged; strict version checks and the worker compatibility key remain stable. Its new source revision, release tag and SHA512 identify the hotfix separately.
Validation used this exact binary and the real beta9 runtime on reserved RTX 4090 GPUs. An unchanged VoxCPM2 checkpoint captured on .22 restored on .19 in 13.56–14.34 s and .22 in 11.64–13.24 s, retaining its nonce and identical audio. The deployed runtime reproduced a 77.36 s managed restore; a paired private .22 control took 19.31 s. Registered host memory and GPU state also passed, with restore improving from 12.05 to 7.23 s. The published asset was downloaded through the Dockerfile URL and verified byte-identical to the tested binary.
Some warm deployed restores were faster; these tests establish removal of a compaction path, not a guaranteed seven-second restore or production p99. No scheduler-free 5090 GPU was available for this artifact's GPU test. The runtime dependency is approved and merged; the artifact remains a prerelease and production has not been changed.