Summary

• treat non-identity Content-Encoding values as binary in the lambda-edge adapter
• base64-encode compressed responses so CloudFront receives valid payloads
• add a regression test that exercises the compress middleware through the adapter

Fixes #4254

Validation

• bunx vitest run src/adapter/lambda-edge/handler.test.ts
• bunx eslint src/adapter/lambda-edge/handler.ts src/adapter/lambda-edge/handler.test.ts
• git diff --check