[FEAT] Add integration tests against DynamoDB Local for AWS templates

[colbytimm]

Summary

Once AWS Lambda templates exist (depends on issues #49, #50, #51, #52), add integration tests that run against DynamoDB Local in CI. DynamoDB Local is a lightweight Docker image provided by Amazon that supports the full DynamoDB API. This validates the DynamoDB repository code works against a real DynamoDB-compatible API.

Category: testing, aws

Depends on: #49, #50, #51, #52 (AWS Lambda template implementations)

Acceptance Criteria

• GHA workflow for each language adds a test-integration-aws job
• DynamoDB Local (amazon/dynamodb-local) runs as a Docker service container
• AWS_ENDPOINT_URL (or SDK-specific endpoint override) points the SDK at the local instance
• Integration tests for each template:
  • Create the DynamoDB table with correct key schema as test setup
  • Run all 5 CRUD operations (create, get by ID, list, update, soft-delete)
  • Assert correct item structure and attribute values
  • Clean up the table in teardown
• Makefile adds test-integration target
• Tests are AWS-variant only

Implementation Notes

DynamoDB Local in GHA

services:
  dynamodb:
    image: amazon/dynamodb-local:latest
    ports:
      - 8000:8000

Connection details:

• Endpoint: http://localhost:8000
• Region: Any valid region string (e.g., us-east-1)
• Credentials: Any non-empty string (DynamoDB Local doesn't validate)

Table Schema

The integration tests should create a table matching the template's expected schema:

Table Name: from DYNAMODB_TABLE_NAME env var
Partition Key: id (String)

SDK Endpoint Override per Language

• Python (boto3): endpoint_url="http://localhost:8000" in client constructor
• TypeScript (AWS SDK v3): endpoint: "http://localhost:8000" in DynamoDBClient config
• Go (aws-sdk-go-v2): aws.EndpointResolverWithOptionsFunc or BaseEndpoint
• .NET (AWSSDK): ServiceURL = "http://localhost:8000" in AmazonDynamoDBConfig