v0.5.7

Fix ConPTY pipe handle lifecycle on Windows 11 24H2

Stop closing the ConPTY-side pipe ends (pipe_in_read, pipe_out_write)
immediately after CreatePseudoConsole. On Windows 11 24H2 (build 26100),
CreatePseudoConsole does not reliably duplicate these handles internally,
so closing them severs the I/O path — resulting in 0 bytes ever appearing
in the output pipe despite a valid HPCON handle and running child process.

Now store these handles on the ConPtyProcess instance and close them only
in close(), after ClosePseudoConsole. Also fix error cleanup paths to
close all four pipe ends on failure.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>