Summary

Store newly uploaded transaction receipts in private Cloudflare R2 storage while preserving compatibility with existing locally stored receipts.

Changes

• Upload new receipt files to ownership-scoped R2 keys under receipts/<userId>/.
• Retrieve protected receipts from R2 after transaction ownership validation.
• Return receipt content with the correct MIME type, extension, length, and private cache headers.
• Delete R2 receipt objects using best-effort cleanup.
• Preserve read and delete compatibility for legacy files stored under RECEIPT_UPLOAD_DIR.
• Return a clear service error when R2 storage is not configured.
• Improve AI structured-response typing by inferring output types directly from Zod schemas.
• Update API, R2 storage, environment, and project-memory documentation.