Bootstrap should reject multiline or malformed Treehouse version output

[Moshik21]

Problem

Firstmate's bootstrap needs Treehouse >=2.0.1 and durable lease support for guarded pool recovery and cleanup. The prior check could accept multiline treehouse --version output when the first line was a supported canonical version, such as:

v2.0.1
unexpected diagnostic

That can treat a malformed or wrapped executable as compatible even though downstream lifecycle safety depends on canonical version and lease behavior.

Expected behavior

Accept exactly one canonical version line at or above v2.0.1, then retain the existing durable-lease capability check. Reject multiline, malformed, pre-floor, or lease-incompatible output through the existing installation diagnostic.

Contribution

PR #1247 implements the bounded correction and regression coverage. Its configured validation is green with low risk. It preserves the existing upgrade-consent path, backend scoping, durable lease check, and guarded cleanup behavior.

Because the repository belongs to kunchenguid, an upstream maintainer must review and merge the contribution.

[Moshik21]

@kunchenguid, the linked contribution is green and ready for upstream review. We cannot assign or merge it with the contributor account, so please review and merge #1247 when convenient.

[Moshik21]

@kunchenguid, the portable-serial failure is fixed on contribution head 7b90bf2: the two affected test doubles now report canonical Treehouse v2.0.1 while retaining lease-help behavior. The replacement CI run https://github.com/kunchenguid/firstmate/actions/runs/30467820310 and policy run https://github.com/kunchenguid/firstmate/actions/runs/30467820811 are waiting for upstream approval of fork workflows (). Please approve those workflows so the contribution can complete CI.