(core): support CloudFormation Metadata Context in synthesized templates #39606

Describe the feature

Add typed AWS CDK APIs for writing the advisory CloudFormation com.aws.cloudformation.Context block at resource and template level. The API should preserve rationale, invariants, change-safety guidance, provenance, dependencies, architecture references, and ownership in synthesized templates.

Use Case

CDK source often contains design intent that is absent from the synthesized and deployed CloudFormation template. Engineers and automated tools inspecting a stack later need that context to evaluate infrastructure changes safely.

Proposed Solution

Implement the API approved in RFC 994 through PR #38381:

• CfnResourceMetadataContext applies complete Context values to selected CfnResource constructs during synthesis.
• CfnTemplateMetadataContext writes template-level Context.
• Public structs and enums mirror the published CloudFormation Metadata Context schema.
• Existing applications remain unchanged unless they call the new APIs.

Other Information

• RFC tracking issue: Structured Design Context in Synthesized Templates aws-cdk-rfcs#994
• Accepted RFC PR: RFC 994: Structured design context in synthesized templates aws-cdk-rfcs#981
• CloudFormation schema: https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-attribute-metadata.html#aws-attribute-metadata-context-schema

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS CDK Library version

N/A (framework feature request)

AWS CDK CLI version

N/A (framework feature request)

Environment details

N/A (framework feature request)