Show stderr output of agent processes

[makenowjust]

Ref #758

Changes

• Change stdio property of the setting on spawning agents from "ignore" to "inherit".
  • Then, stderr output of agent processes will be shown.
  • It may prevent issues like Recheck throws error Error: write EPIPE #758.

[codecov-commenter]

Codecov Report

Merging #768 (8ac2819) into main (dab2c68) will not change coverage.
The diff coverage is 100.00%.

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@@            Coverage Diff            @@
##              main      #768   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           66        66           
  Lines         2863      2863           
  Branches       489       488    -1     
=========================================
  Hits          2863      2863           

Impacted Files	Coverage Δ
packages/recheck/src/lib/agent.ts	100.00% <100.00%> (ø)

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