feat(litellm): async retain, reflect support, and API cleanup #448

Job	Run time
build-docs	1m 49s
test-rust-cli	2m 2s
build-control-plane	54s
build-api-python-versions (3.11)	9s
build-typescript-client	14s
build-api-python-versions (3.13)	9s
build-api-python-versions (3.12)	11s
test-python-client	1m 6s
test-integration	1m 10s
build-python-packages (hindsight-api, hindsight-api)	11s
build-python-packages (hindsight-client, hindsight-clients/python)	12s
test-litellm-integration	17s
build-python-packages (hindsight-all, hindsight)	7s
build-python-packages (hindsight-embed, hindsight-embed)	6s
test-rust-client	1m 45s
lint-helm-chart	5s
test-embed	1m 5s
test-typescript-client	1m 53s
verify-generated-files	4m 10s
test-api	5m 20s
build-docker-images (api-only, api)	5m 54s
build-docker-images (cp-only, control-plane)	4m 2s
build-docker-images (standalone, standalone)	6m 15s
test-doc-examples	1m 34s
	40m 40s

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