fix(coding-agent): remove detached: true on Windows to fix pwsh.exe stdio (#4013)

On Windows, spawn(..., { detached: true }) prevents pwsh.exe (PowerShell) from
producing any stdout/stderr through pipe streams. This is because detached creates
a new process group which breaks pwsh's console host communication.

bash.exe and other cygwin/msys2 shells are unaffected by detached: true, but
they don't need it either -- on Windows, killProcessTree() already uses
taskkill /F /T /PID which kills the process tree by PID regardless of
whether the process was spawned detached.

The detached flag only matters on Unix, where kill(-pid, SIGKILL) requires a
process group that is only created via detached: true.

Fixes #4012

packages/coding-agent/src/core/tools/bash.ts

@@ -83,7 +83,7 @@ export function createLocalBashOperations(options?: { shellPath?: string }): Bas
 				}
 				const child = spawn(shell, [...args, command], {
 					cwd,
-					detached: true,
+					detached: process.platform !== "win32",
 					env: env ?? getShellEnv(),
 					stdio: ["ignore", "pipe", "pipe"],
 				});