Investigate and fix minimum_version semantics in trezorlib

[coderabbitai]

Summary

Investigate and correct the semantics and use of per-model minimum_version in trezorlib.

PR #7212 consolidates model metadata in python/src/trezorlib/_modeldata/ and adds model-specific minimum firmware versions. During review, it was noted that trezorctl warns that firmware is outdated whenever this threshold is not met. That behavior may not be appropriate if these values represent the first firmware release for a model rather than a mandatory upgrade floor.

Required investigation

• Define the intended contract for ModelData.minimum_version:
  • whether it is the first released firmware version,
  • a minimum supported firmware version for host operations,
  • or another compatibility threshold.
• Trace every trezorlib and trezorctl consumer of this metadata and document how it affects user-visible warnings and behavior.
• Decide whether the field should be enforced, renamed, split into distinct metadata, or removed until there is a valid use case.
• Ensure the model values are accurate if the field remains.

Affected areas

• python/src/trezorlib/_modeldata/
• python/src/trezorlib/models.py
• Firmware/CLI version-checking and warning paths in python/src/trezorlib/

Acceptance criteria

• The meaning of minimum_version is documented and unambiguous.
• trezorctl does not emit misleading “outdated firmware” warnings based solely on model-release metadata.
• All consumers implement the agreed semantics consistently.
• Tests cover the intended warning/compatibility behavior and the relevant model-version cases.

Requested by @obrusvit.

Related:

• PR refactor model definitions in python/trezorlib #7212: refactor model definitions in python/trezorlib #7212
• Review discussion: refactor model definitions in python/trezorlib #7212 (comment)

[obrusvit]

Maybe @matejcik has some context?

[matejcik]

minimum_version was always "lowest version supported by this trezorlib (without warnings)"
technically you could have one version for all of trezor_core

"lowest released firmware for a given model" seems like a useless value

[matejcik]

the reason for minimum_version defined as such is twofold:

1. code-facing, we will drop compatibility hacks for versions lower than minimum_version
2. user-facing, we can also bump this when releasing a major security upgrade to push users towards it