docs(lambda): ensure consistent environment variable management

[azarboon]

This update improves the AWS Lambda documentation by introducing a single source of truth for environment variables using TypeScript. It addresses the common issue of environment variable inconsistencies between Lambda function code and AWS CDK infrastructure.

Key Improvements:

• Defines environment variables in a shared env.ts module.
• Ensures type safety and consistency across Lambda and CDK.
• Reduces duplication and minimizes the risk of misconfigured environment variables.
• Enhances maintainability and developer experience.

By implementing this approach, developers can catch errors at compile time, benefit from improved IDE support, and prevent mismatches between deployment and runtime environments.

Issue # (if applicable)

Closes #.

Reason for this change

Environment variables are often defined separately in Lambda function code and AWS CDK, leading to potential inconsistencies, deployment mismatches, and runtime failures. By centralizing env var definitions in a TypeScript module, this approach improves reliability, prevents human errors, and enforces stricter type safety. It also makes the codebase more maintainable by reducing duplication and ensuring that changes to environment variables propagate correctly across the application and infrastructure.

Description of changes

• Added a new section to the AWS Lambda documentation explaining how to manage environment variables with a single source of truth in TypeScript.
• Provided step-by-step instructions for defining, referencing, and using a shared env.ts module in both Lambda function code and AWS CDK infrastructure.
• Included example code snippets demonstrating best practices for env var management.
• Improved error handling considerations, ensuring that missing environment variables are properly managed.

Describe any new or updated permissions being added

Description of how you validated changes

I ran the provided code examples locally to ensure correctness and consistency between the Lambda function and AWS CDK infrastructure. The Lambda function successfully retrieved environment variables from the centralized env.ts module, and the AWS CDK deployment correctly passed the expected environment variables to the Lambda function. No runtime errors or deployment issues were encountered.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[aws-cdk-automation]

(This review is outdated)

✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.21%. Comparing base (6df9bfe) to head (065c0b9).

Additional details and impacted files

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Flag	Coverage Δ
suite.unit	82.21% <ø> (ø)

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Components	Coverage Δ
packages/aws-cdk	∅ <ø> (∅)
packages/aws-cdk-lib/core	82.21% <ø> (ø)

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 065c0b9
• Result: FAILED
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