Feat add endpoint to validate and preview import files before ingestion

[BrayanMQ]

feat(imports): pre-ingestion validation and preview endpoint

Closes #152

Summary

Adds POST /api/imports/preview for enterprise API keys. Clients upload a CSV (multipart field file) with a required address column (case-insensitive header). The handler parses and validates each row’s Stellar address format, returns aggregate counts, bounded preview samples, and row-level errors with line numbers. No data is persisted.

Requirements (issue)

Requirement	Implementation
Validate schema + preview summary	CSV header must include address; response includes summary, preview, rowErrors
Row-level errors with line references	rowErrors[] with line, optional column, code, message
No persistence	In-memory buffer only
Bounded preview	Caps on valid/invalid sample sizes in importPreviewService
Summary counts	validRows, invalidRows, totalRowsScanned, truncation flags when applicable
Limit upload / parse time	512 KiB file limit (multer + service), 10k rows cap, 5s validation budget
Sanitized parser errors	Malformed CSV returns generic message; no stack or raw parser internals

How to test

Automated

npx vitest run src/__tests__/imports.test.ts
# or
npm test

Manual (with npm run dev)

curl -sS -X POST "http://localhost:3000/api/imports/preview" \
  -H "X-API-Key: test-enterprise-key-12345" \
  -F "file=@path/to/your.csv"

Sample CSV:

address
GABC7IXPV3YWQXKQZQXQZQXQZQXQZQXQZQXQZQXQZQXQZQXQZQXQZQXQ

Files changed (this PR)

• package.json, package-lock.json — multer, csv-parse, @types/multer
• src/lib/stellarAddress.ts — shared isValidStellarAddress
• src/services/identityService.ts — uses shared validator
• src/services/importPreviewService.ts — parse, validate, limits, response shape
• src/routes/imports.ts — POST /preview, enterprise auth, multipart upload
• src/app.ts — mount /api/imports
• src/__tests__/imports.test.ts — malformed CSV, schema, partial errors, auth, 413, UTF-8

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[Baskarayelu]

Please resolve the conflicts

[BrayanMQ]

@Baskarayelu done!

[Baskarayelu]

Please revert the changes made to the package-lock.json file.