Add suggestions for CSV column verification implementation

[Copilot]

Reviewed the CSV column verification feature added in the previous commit and identified critical issues and improvements needed.

Issues Identified

Critical Bug: verifyColumns.ts line 19 accesses rawData[0] without checking if the array is empty, causing runtime errors when CSV files contain only headers with no data rows.

Missing Test Coverage: The verifyColumns function lacks dedicated tests for:

• Happy path with all required columns present
• Missing columns scenario
• Empty CSV file edge case

Robustness: Column matching is case-sensitive, which may cause false positives if CSV headers have different casing than expected.

Suggested Improvements

// Add guard clause before accessing rawData[0]
export const verifyColumns = (
  rawData: ReadonlyArray<Record<string, string>>,
  columnsToVerify: ReadonlyArray<string>,
) => {
  if (columnsToVerify.length === 0 || rawData.length === 0) {
    return;
  }
  
  const missingColumns = columnsToVerify.filter((col) => !Object.keys(rawData[0]).includes(col));
  // ...
};

Awaiting confirmation to implement these fixes.

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