Remove SIGWINCH from signal kill set

[ArasanDev]

Type of Change

• Bug fix

Motivation and Context

Fixes #1747.

SIGWINCH is a terminal geometry notification — its POSIX-defined purpose is to inform a process that the controlling terminal's window size has changed. It is not a process-control signal and has no meaningful effect when delivered via kill(2) to a process without a controlling terminal.

ProcessIO.signalSet included SIGWINCH alongside SIGTERM, SIGINT, SIGUSR1, and SIGUSR2. In non-TTY mode (console == nil), handleProcess iterates signalSet and forwards every received signal through process.kill(sig). This caused host terminal resize events to produce a logged error on stderr:

failed to send signal: ["error": invalidArgument: "missing signal in xpc message", "signal": 28]

There is no valid use case for forwarding SIGWINCH as a kill signal in non-TTY mode — the container has no pseudo-terminal whose geometry could change.

TTY mode is unaffected. In TTY mode (console != nil), the signals task is never added to the task group. A separate winchHandler registers independently for [SIGWINCH] and routes it to process.resize(), which is the correct handler. Removing SIGWINCH from signalSet does not touch this path.

As a secondary benefit, this also eliminates a redundant DispatchSourceSignal registration for SIGWINCH in TTY mode: previously both signals (via signalSet) and winchHandler registered for the same signal, with signals never consumed in the TTY branch.

Testing

• Tested locally
• make test passes