test(7.15): align EOS and Solana release vectors

[BitHighlander]

Summary

• require the corrected EOS SLIP-48 updateauth digest produced by firmware 7.15
• keep opaque/binary Solana messages behind AdvancedMode
• verify bounded printable Solana login text signs without AdvancedMode on 7.15
• start both Solana policy cases from factory state so session policy cannot leak across tests

Evidence

• firmware CI exposed both stale expectations independently
• EOS digest 5938294e... was independently verified in da90cd94071356ce59fd5c9ea2b26652f217dae5
• Solana behavior is covered by firmware unit tests for plain text, binary/control/UTF-8 payloads, and embedded signer keys
• python3 -m py_compile tests/test_msg_eos_signtx.py tests/test_msg_solana_signtx.py

This branch starts at the firmware release stack's exact prior companion SHA. The PR is 2 files and 30 changed lines; it does not import unrelated alpha companion work.

[BitHighlander]

Superseded by #226 on the canonical reconcile/upstream-sync lineage. Firmware 7.15 now pins only commits on that canonical ancestry; this release-specific branch is no longer referenced.