[fix][evaluation] ExptInsightAnalysisService add start/end time

[xueyizheng]

What type of PR is this?

ExptInsightAnalysisService add start/end time for InsightReport analysis

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[CozeLoop]

Code Review Summary: Added validation and API design feedback for start/end time propagation in insight analysis, flagged a must-fix for interface change impacting mocks/tests, and marked safe changes. Please see inline comments for actionable guidance.

[codecov]

Codecov Report

❌ Patch coverage is 96.00000% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...evaluation/infra/mq/rocket/consumer/expt_export.go	0.00%	1 Missing ⚠️

@@           Coverage Diff           @@
##             main     #284   +/-   ##
=======================================
  Coverage   68.08%   68.09%           
=======================================
  Files         568      568           
  Lines       50548    50557    +9     
=======================================
+ Hits        34418    34425    +7     
- Misses      13459    13460    +1     
- Partials     2671     2672    +1     

Flag	Coverage Δ
unittests	68.09% <96.00%> (+<0.01%)	⬆️

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

Files with missing lines	Coverage Δ
...d/modules/evaluation/application/experiment_app.go	77.80% <100.00%> (+0.12%)	⬆️
backend/modules/evaluation/domain/entity/event.go	0.00% <ø> (ø)
...evaluation/domain/service/insight_analysis_impl.go	98.04% <100.00%> (+0.03%)	⬆️
...ackend/modules/evaluation/infra/rpc/agent/agent.go	66.66% <100.00%> (ø)
...evaluation/infra/mq/rocket/consumer/expt_export.go	0.00% <0.00%> (ø)

... and 2 files with indirect coverage changes

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