linux-smoke: select runner-compatible artifact packages (TIN-1422)

[Jesssullivan]

Summary

• filter mixed release workflow artifacts to runner-compatible package types before invoking the Linux postinstall harness
• keep Ubuntu hosted smokes on .deb packages and rpm-family runners on .rpm packages
• add a static workflow regression check so the mixed-artifact bug does not come back

Root Cause

Run 26204503344 proved the tcfs-linux-smoke backend was reachable and installed both Ubuntu .deb packages, then failed because dist-linux-x86_64 also contained the daemon .rpm and the Ubuntu harness attempted to install it with rpm.

Verification

• bash scripts/test-linux-postinstall-workflow.sh
• git diff --check

Tracker

TIN-1422 / TIN-1540 unblocker. After this workflow change lands, rerun Linux postinstall smoke against rc3 artifact dist-linux-x86_64 from release run 26204080480.

[Jesssullivan]

Validation run for the mixed-artifact package filter passed:

• Run: https://github.com/Jesssullivan/tummycrypt/actions/runs/26204598522
• Branch/ref: codex/linux-smoke-package-filter-tin-1422@a83684c
• Package source: rc3 release workflow artifact dist-linux-x86_64 from run 26204080480
• Environment: tcfs-linux-smoke

Evidence from uploaded artifact:

• storage endpoint was HTTPS with enforce_tls=true; daemon storage: [ok]
• only Ubuntu-compatible .deb packages were installed; the .rpm was no longer selected
• tcfs index inspect returned status: visible for ci-smoke/0.12.13-rc3/postinstall-1.txt
• FUSE mounted seaweedfs+https://.../tcfs/gha/linux-postinstall/v0.12.13-rc3/26204598522-1
• exact hydrate matched 59-byte seeded content
• evict/rehydrate gate completed
• mutation through the mounted FS was pulled back from remote and matched the 59-byte expected content

This validates the workflow fix. After #429 lands, rerun the same smoke on main for closure-grade TIN-1422/TIN-1540 evidence.