[Other] support video_fps args for video bench

[Wanglongzhi2001]

Motivation

💡 If this PR is a Cherry Pick, the PR title needs to follow the format by adding the [Cherry-Pick] label at the very beginning and appending the original PR ID at the end. For example, [Cherry-Pick][CI] Add check trigger and logic(#5191)

💡 如若此PR是Cherry Pick，PR标题需遵循格式，在最开始加上[Cherry-Pick]标签，以及最后面加上原PR ID，例如[Cherry-Pick][CI] Add check trigger and logic(#5191)

Modifications

Usage or Command

Accuracy Tests

Checklist

• Add at least a tag in the PR title.
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[paddle-bot]

Thanks for your contribution!

[Copilot]

Pull request overview

该 PR 旨在为 OpenAI 协议的 completions / chat.completions 请求增加一个临时参数 video_fps，以支持视频理解相关 benchmark 在请求侧传入抽帧 FPS 信息。

Changes:

• 在 CompletionRequest 中新增可选字段 video_fps
• 在 ChatCompletionRequest 中新增可选字段 video_fps

[Copilot]

这里新增的 video_fps 目前只会被透传进 to_dict_for_infer() 的 req_dict，但在仓库内的输入处理链路中未找到任何地方读取/应用该字段（搜索仅在 protocol.py 中出现）。这会导致基准测试传入 video_fps 也不会影响实际抽帧逻辑。建议在预处理阶段将其映射到视频 item 的 fps（如 messages/multimodal_data 的 video part），或改为复用现有的 mm_processor_kwargs.video_fps 机制并在处理器侧消费该参数。

[Copilot]

新增请求字段后建议补充单测覆盖：例如验证当用户传入 video_fps 时，CompletionRequest/ChatCompletionRequest.to_dict_for_infer() 的输出会包含该字段（且为预期类型/取值）。仓库已有 openai protocol 相关测试（tests/entrypoints/openai/*），增加回归测试能避免后续重构导致该临时参数被悄然丢弃。

[Copilot]

当前 PR 标题使用了 [Other]，但仓库 PR 模板的 tag list 中是 [Others]（见 .github/pull_request_template.md 的 Checklist）。建议把标题 tag 调整为已有的 [Others] 或新增语义更明确的 tag，以满足仓库约定。

[codecov-commenter]

Codecov Report

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Additional details and impacted files

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