[optimize] Refactor BatchMeta to ordinary class

[0oshowero0]

1. Refactor BatchMeta from @dataclass to regular class
2. Remove unnecessary serialization fix for dataclass BatchMeta

[ascend-robot]

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[Copilot]

Pull request overview

This PR refactors BatchMeta from a @dataclass into a regular __slots__-based class and removes the previously-added serialization workaround that existed because msgspec auto-serialized dataclasses (bypassing enc_hook).

Changes:

• Convert BatchMeta to a regular class with __slots__ and an explicit __init__ performing normalization/validation.
• Remove the BatchMeta-specific msgpack Ext serialization path in serial_utils (and associated preprocessing).
• Remove the __setstate__-specific test coverage for the old dataclass deserialization path.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
transfer_queue/utils/serial_utils.py	Removes BatchMeta-specific Ext handling; adjusts msgpack custom type codes.
transfer_queue/metadata.py	Refactors BatchMeta into an ordinary class with __slots__ and explicit initialization/validation.
tests/test_metadata.py	Removes the __setstate__ read-only production_status regression test tied to the old dataclass behavior.

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[ascend-robot]

CLA Signature Pass

0oshowero0, thanks for your pull request. All authors of the commits have signed the CLA. 👍

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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[ascend-robot]

CLA Signature Pass

0oshowero0, thanks for your pull request. All authors of the commits have signed the CLA. 👍

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

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