fix(windows): strip NUL padding from wsl.exe distro names

[patil2001]

Summary

First use of llm-cold-storage.sh --execute on any host silently archived nothing: the script ensures its log directory but never creates $COLD_DIR, and running without -e, the failed mv/ln were non-fatal while the summary still counted the model as ARCHIVED. The cold target is now created up front.

AI Assistance

AI-assisted dry-run of the archive path. The author traced the silent-failure chain and is responsible for the final diff.

Release Lane

• Stable hotfix targeting release/2.6.x
• Mainline change targeting main
• Next-minor work targeting the next feature/minor release
• Not sure; reviewer should help classify

Stable hotfix reason:

Not targeting the stable release branch directly.

Changed Surface

• Docs only
• Tests only
• Dashboard UI
• Installer
• Core runtime
• Dashboard API
• CI workflows

Validation

• bash -n ods/scripts/llm-cold-storage.sh - passed.
• Dry-run executed locally post-change (no models present).