fix: guard treemap empty-data crash; normalize source_domains/target_modules string→object

[simongonzalezdc]

• Treemap: guard against empty source_treemap.data to prevent D3 crash on d.data.name.length
• Creative DNA Sankey: normalize source_domains/target_modules string entries to {domain, repo_count, total_files} objects to prevent crash on .domain.replace

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Summary by CodeRabbit

• Bug Fixes
  • Architecture "Source Treemap" chart now displays an informative message when no source structure data is available
  • Universe "Creative DNA Sankey" chart improved to handle various data input formats consistently

[coderabbitai]

Caution

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between f825557 and df1bc9f.

📒 Files selected for processing (1)

• archaeology/visualization/template.html

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📝 Walkthrough

Walkthrough

The PR adds defensive handling to two visualization charts in the template file. The Source Treemap now checks for an empty modules array and displays a fallback message instead of attempting to render a treemap with no data. The Creative DNA Sankey normalizes its input data by converting raw string entries into structured objects with the expected field shapes before constructing nodes and links.

Changes

Visualization Chart Robustness

Layer / File(s)	Summary
Source Treemap empty state handling archaeology/visualization/template.html	When the computed modules array is empty, the chart displays "No source structure data available" and returns without constructing the D3 treemap.
Creative DNA Sankey input normalization archaeology/visualization/template.html	dna.source_domains and dna.target_modules string entries are converted to objects with expected fields: { domain, repo_count: 0, total_files: 0 } for sources and { label, domain } for targets.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/template-viz-guards

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