Refuse unrecognized CI run conclusions instead of reporting clear health

[devantler]

🤖 Generated by the Agentic Engineer

Problem

A current branch run with an unrecognized conclusion is discarded by the classifier, which exits 0 with no red rows. A malformed outcome is therefore indistinguishable from clear health.

Reproduced against current main 3538221 using the shipped public command and an isolated offline fixture.

Proposed direction

Validate the supported conclusion vocabulary and consistency with a supplied run status before selecting the latest settled outcome.

Acceptance criteria

• Unknown conclusions and inconsistent completed/pending states return exit 2 with no classification; recognized pending and cancelled runs preserve known failures.
• Add a failing regression first, preserve valid behavior, and verify the merged public command.

Size: S. Part of #38.

[devantler]

🤖 Generated by the Agentic Engineer

Delivered in #365, merged at 3e7afb4 after clean current-head review and CI. The actual merged collectors and installed wrapper passed their public-command tests, and exact-main CI passed all 32 jobs. Closing as completed.