[X-LightYear]

Summary

• keep parsed numeric values numeric in CSV exports
• preserve formula protection for string cells
• add regression coverage for negative metric values

Problem

The shared CSV helper treated every text value beginning with - as a possible spreadsheet formula. Metric Explorer supplies parsed sample values as numbers, so negative values were exported with a leading apostrophe and opened as text.

Fix

Only string-like values retain the formula-protection prefix. Numeric values are serialized without the prefix.

Testing

• pre-fix focused regression failed: escapeCsvCell(-3.5) returned "'-3.5"
• download.test.ts and resourceCsvImport.test.ts: 26 passed
• frontend lint: 0 errors, existing warnings only
• npm run build: TypeScript/Vite completed; existing distribution-license verification rejected the toggle-selection source/license mismatch

Fixes #7336