feat(aws): add Lambda serverless compute provider

[atharva-nagane]

Closes #102

Summary

• Adds aws_lambda.rs — 6 operations covering the full Lambda function lifecycle
• New aws-sdk-lambda = "1.30.0" dependency (consistent with other AWS SDK crates)
• Test file with 6 tests; usage guide at examples/aws/compute/lambda.md

Operations

Function	Description
create_function	Deploy a function from a ZIP artifact with runtime + IAM role
delete_function	Remove a function
list_functions	Enumerate all functions, returns Vec<String> of names
get_function	Print runtime, handler, state, last modified
invoke_function	Synchronous call with optional JSON payload
update_function_code	Push a new ZIP deployment package

Test plan

• cargo build passes with the new dependency
• cargo test aws_lambda runs without compile errors
• Integration tests require AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, valid Lambda role ARN