Use a public immutable Hermes skill smoke fixture

[JulioMCruz]

Summary

• replace the private EQLTY auxiliary skill file, which returns 404 to unauthenticated CI
• use a public file pinned to the same immutable ethskills commit as the primary smoke fixture
• preserve the multi-file installer assertion

Validation

• both raw fixture URLs return 200
• bash -n tests/hermes/smoke.sh
• Hermes patch unit tests pass
• git diff --check

This addresses the only remaining Hermes failure in main run 31455470369 after the upstream guard fix.