Cross-folder mermaid coverage check — sum every ```mermaid opening fence across the analysis-folder source artifacts (excluding article.md / README.md / translation siblings) so the orchestrator can detect when the aggregator dropped a diagram.
Rule census: extracted from
`scripts/validate-article.ts` lines 759–787
(`countSourceArtifactMermaidOpenings`). Logic is
byte-identical to the original.
Description
Cross-folder mermaid coverage check — sum every ```mermaid opening fence across the analysis-folder source artifacts (excluding article.md / README.md / translation siblings) so the orchestrator can detect when the aggregator dropped a diagram.
@author Hack23 AB @license Apache-2.0