Secure file uploads and CDN delivery for Next.js with presigned tokens and multipart support.

• Supports server-side uploads via put() and client-side uploads with presigned tokens via handleUpload() to avoid exposing credentials
• Handles files up to 500MB with automatic multipart upload; client uploads bypass the 4.5MB serverless function limit
• Includes file listing with cursor-based pagination, deletion, and content-type management for proper browser handling
• Prevents 16 documented issues including token expiration on large files, filename collisions, cross-browser compatibility, and pathname validation errors