feat: add TTL archival lifecycle support

[aron23]

Summary

• implement TTL-aware schema provisioning across Go, TypeScript, and Python helpers
• add a CDK archival construct plus stream archiver Lambda for DynamoDB TTL removals into S3 with Glacier lifecycle controls
• document the new retention flow and extend the multilang CDK example to exercise it

Verification

• go test ./pkg/schema
• npm --prefix ts run test:unit
• npm --prefix ts run build
• python3 -m pytest py/tests/unit/test_schema.py
• python3 -m ruff check py/src/theorydb_py/schema.py py/src/theorydb_py/mocks.py py/src/theorydb_py/init.py py/tests/unit/test_schema.py
• npm --prefix examples/cdk-multilang run test

Refs pay-theory/compliance-advisor#19