Split Node and edge runtime packaging

[dkropachev]

Summary

• split Node-only runtime/compression/TLS code from the Edge runtime entrypoints
• add explicit Edge exports for low-level and document clients
• make @aws-sdk/lib-dynamodb optional peer-only at runtime and add Node >=20 engine metadata
• tighten JavaScript config validation and drop unused leftover exports
• replace runtime package.json import with a build-time package version define

Verification

• npm run verify
• npm run test:integration without INTEGRATION_TESTS set
• npm pack --dry-run
• Node ESM import smoke test
• Node CJS require smoke test
• explicit Edge subpath smoke test
• Edge bundle scan for Node builtins and @smithy/node-http-handler