[feat][backend] add extra_output field to ListExperimentResultOApi response

[VinCinx]

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feat

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[feat][backend] add extra_output field to ListExperimentResultOApi response

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为 ListExperimentResultOApi 接口返回值增加 extra_output 字段

(Optional) More detailed description for this PR

en: Add extra_output (containing output_type and url) to the OpenAPI experiment result response. Previously this field was only available via the internal BatchGetExperimentResult API. Changes include: updating the OpenAPI IDL, regenerating kitex_gen, adding entity-to-DTO conversion, injecting fileProvider for URI-to-URL signing, and fixing the private convertor in the experiment package.

zh: 为 OpenAPI 实验结果接口补齐 extra_output 字段（含 output_type 和签名后的 url）。此前该字段仅在内部接口 BatchGetExperimentResult 中返回。改动涉及 IDL 更新、kitex 代码生成、DTO 转换逻辑、fileProvider 注入签名，以及 experiment 包内私有 convertor 的同步修复。

(Optional) Which issue(s) this PR fixes

N/A

[codecov]

Codecov Report

❌ Patch coverage is 68.11594% with 22 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...modules/evaluation/application/eval_openapi_app.go	54.16%	20 Missing and 2 partials ⚠️

❌ Your patch status has failed because the patch coverage (68.11%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

@@            Coverage Diff             @@
##             main     #554      +/-   ##
==========================================
+ Coverage   77.60%   78.06%   +0.45%     
==========================================
  Files         670      670              
  Lines       75995    76214     +219     
==========================================
+ Hits        58979    59494     +515     
+ Misses      13565    13283     -282     
+ Partials     3451     3437      -14     

Flag	Coverage Δ
unittests	78.06% <68.11%> (+0.45%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...luation/application/convertor/evaluator/openapi.go	96.53% <100.00%> (+4.63%)	⬆️
...uation/application/convertor/experiment/openapi.go	89.82% <100.00%> (+6.25%)	⬆️
...d/modules/evaluation/application/experiment_app.go	84.36% <100.00%> (+0.02%)	⬆️
...evaluation/domain/service/expt_result_aggr_impl.go	79.75% <100.00%> (+0.08%)	⬆️
...modules/evaluation/application/eval_openapi_app.go	90.17% <54.16%> (-2.11%)	⬇️

... and 27 files with indirect coverage changes

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