CSV Import: Commit endpoint (persist transactions)

[azunaVT]

Epic: Import

Description

Persist transactions from a CSV import after preview confirmation.

Endpoint

• POST /api/v1/imports/csv/commit

Acceptance Criteria

• Accepts CSV file or normalized payload
• Creates an Import record scoped to household
• Inserts transactions in a single DB transaction
• Returns:
  • number of rows inserted
  • number of rows skipped
• Fails cleanly on invalid data
• Request spec included