AppSync GraphQL API with DynamoDB and S3 presigned URL generation

[mate329]

A complete AWS CDK infrastructure-as-code project in Python 3.12 that demonstrates a serverless architecture combining:

• AppSync GraphQL API with API Key authentication for real-time data operations
• DynamoDB as the primary database for item storage and retrieval
• S3 bucket for file storage with secure presigned URL access
• Lambda resolver that generates secure, time-limited presigned URLs for S3 object access

The project includes GraphQL queries and mutations for:

• all CRUD operations for all items in DynamoDB
• Generating presigned URLs for secure S3 file downloads