FlowAnalysis diffs an ordered sequence of audit reports — the output of
tester.auditFlow — so each step's introduced and resolved findings are
explicit. Instead of "here are N reports" it says "opening the dialog
introduced these two issues", matching by the stable fingerprint so a pure
layout shift between steps is not counted as a change.
introducedByInteractions excludes the initial screen's own findings.

This makes interaction-aware auditing actionable — it names the interaction
responsible. Releases attest 1.7.0 (FlowAnalysis, StepDelta) and attest_flutter
1.2.1 (requires it, documents FlowAnalysis in the flow section); attest_cli is
unchanged.