Add Aliyun Elasticsearch CBOR query transport

[vicety]

What changed

• Keep the existing Base64 big-endian float32 JSON query transport as the default.
• Add an optional cbor-f32le transport that sends query vectors as raw little-endian float32 bytes in application/cbor requests.
• Add Aliyun Elasticsearch case configuration, environment overrides, and a web UI selector for the query wire format.
• Add the cbor2 optional dependency and documentation for both transports.

Why

Aliyun Elasticsearch supports a raw-f32 CBOR query path in addition to Base64 JSON. Exposing both formats makes the benchmark transport explicit and allows users to compare them without changing client code.

Validation

• python -m compileall passed for the changed Python implementation.
• git diff --check passed.
• The full test suite was not run locally.

[sre-ci-robot]

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