chore: prepare lambda layer catalog

[ava-silver]

What does this PR do?

• Adds the generated Lambda layer catalog.
• Derives runtime maps and default layer versions from the catalog.
• Covers default x86_64 and arm64 layer synthesis.

Motivation

Keep layer runtime and version data in one generated source without changing current behavior.

Testing Guidelines

Not applicable.

Additional Notes

Ruby runtime and layer-name keys remain intentionally distinct to preserve current behavior.

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog

[ava-silver]

• [FEAT] add runtime testing escape hatch #687
• chore: reconcile lambda runtime support #686
• chore: prepare lambda layer catalog #685 👈 (View in Graphite)
• main

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