Quote node labels in deduplication flowchart to prevent <p> injection
Unquoted square brackets in mermaid flowchart nodes (e.g. A[Text]) can
be interpreted as markdown link references by some parsers, causing
<p></p> tags to wrap each label. Using quoted strings (A["Text"]) fixes this.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>