Flows External App Submit

This is step 4 (final) of the Flows app certification flow:

flows-app-brief  →  build  →  flows-code-review  →  flows-design-review  →  flows-external-app-submit (this skill)

This skill does not rerun any review. It verifies the artifacts from the prior three steps and only then invokes the CLI submit command.

Preconditions (show these to the user first)

Before doing anything, print this checklist so the user knows exactly what is being verified:

App-Brief.md exists at repo root and all required frontmatter fields are populated.
The latest reviews/code-review/feedback-round-<N>/code-review-report.md is committed to git and reports Must Fix open: 0.
The latest reviews/design-review/feedback-round-<N>/design-review-report.md is committed to git and reports Average score: X.X with X.X ≥ 3.8.
Certification artifacts are committed — apps submit uses git archive HEAD and silently excludes uncommitted files.
A deploy bundle exists in .cognite-bundles/ and is not older than HEAD.