[feat][evaluation]upgrade llm parse

[tpfz]

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[CozeLoop]

Code review completed. Please see inline comments for specific issues and suggestions. Overall: solid improvements in parsing robustness; a few corrections recommended for error handling flow, signed number parsing in regex fallback, and test flakiness due to strict timing thresholds.

[codecov]

Codecov Report

❌ Patch coverage is 88.09524% with 10 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ion/domain/service/evaluator_source_prompt_impl.go	88.09%	9 Missing and 1 partial ⚠️

@@            Coverage Diff             @@
##             main     #278      +/-   ##
==========================================
+ Coverage   68.02%   68.07%   +0.04%     
==========================================
  Files         568      568              
  Lines       50484    50554      +70     
==========================================
+ Hits        34342    34414      +72     
+ Misses      13473    13469       -4     
- Partials     2669     2671       +2     

Flag	Coverage Δ
unittests	68.07% <88.09%> (+0.04%)	⬆️

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Files with missing lines	Coverage Δ
...ion/domain/service/evaluator_source_prompt_impl.go	76.82% <88.09%> (+4.45%)	⬆️

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