Apply timeout configuration to waza run

[chlowell]

Users set a timeout value in eval configuration and commands like run pass that to CopilotEngine.Execute() via ExecutionRequest.Timeout. The value stops there. It's never realized as a Context timeout, so these commands get the Copilot SDK's default timeout instead. This PR is a quick fix; really the cancellation API needs a refactor (#129)

[Copilot]

Pull request overview

This PR aims to enforce ExecutionRequest.Timeout for Copilot executions by adding a context deadline inside CopilotEngine.Execute when the incoming context has no deadline.

Changes:

• Wrap ctx in context.WithTimeout(ctx, req.Timeout) when ctx has no deadline.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #130   +/-   ##
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  Coverage        ?   73.52%           
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  Files           ?      138           
  Lines           ?    15789           
  Branches        ?        0           
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  Hits            ?    11609           
  Misses          ?     3338           
  Partials        ?      842           

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