/claim #71

Summary

Adds focused Vitest coverage for the CSV import route (src/import/csv.ts).

Covered behaviours:

• Empty request body returns 400
• Unsupported Content-Type returns 400
• Raw text/csv imports generate parameterized insert statements
• JSON-wrapped CSV payloads apply columnMapping
• Multipart requests without a file return 400
• Partial insert failure returns failed statement details

Verification

Not run locally in this environment because dependencies are not installed (node_modules missing). The tests follow the existing JSON import test structure and mock executeOperation the same way.