feat: emit canonical CDK and CloudFormation resource changes for CloudBurn

Goal

Publish a versioned, runtime-validated CloudBurn Resource Change Set so https://github.com/towardsthecloud/cloudburn-monorepo/issues/88 can consume pricing facts without parsing human Markdown or pull-request source.

The authoritative implementation lives in https://github.com/towardsthecloud/github-actions-builder and is release-synced here.

Scope

• Accept paired base/head synthesized templates for CDK.
• Preserve stable stack, construct-path, logical-ID, and resource-type identity.
• Emit complete old/new price-driving properties for modified resources, including EC2 instance type and RDS database class changes.
• Add a tested paired-template CloudFormation producer path before CloudBurn documents CloudFormation as supported.
• Preserve the human-readable CDK comment while appending a hidden, signed-comment-safe canonical payload.
• Validate schema version, source, region, side states, property values, size limits, and usage-assumption snapshot references.
• Document the published-contract deprecation window so CloudBurn can remove its Markdown/source-regex parser.

Acceptance

• Equivalent CDK and CloudFormation fixtures emit the same normalized resource model.
• Added, deleted, and modified resources have explicit old/new states.
• Modified baseline resources prove both old and new pricing inputs.
• Markdown formatting can change without changing the canonical payload.

Consumer dependency: https://github.com/towardsthecloud/cloudburn-monorepo/issues/88

Start by reviewing the authoritative implementation in github-actions-builder and the paired synthesized-template requirement described here. Trace how CDK comments are currently produced, then define the normalized contract against the listed acceptance criteria and validate it with equivalent CDK and CloudFormation fixtures.