Kill Windows process tree on subprocess timeout to unblock proc.communicate()

When a subprocess times out on Windows, proc.kill() only kills the direct
child. Grandchild processes (e.g. installer EXEs spawned by winget) inherit
the pipe write handles and keep them open, causing the subsequent
proc.communicate() call to block indefinitely until every grandchild exits.

Fix by calling taskkill /F /T /PID before proc.communicate() to kill the
entire process tree atomically. Also run windows_processes_to_cleanup in the
timeout path, mirroring what already happens in the normal exit path.

Author: kdeldycke

meta_package_manager/base.py

@@ -827,6 +827,24 @@ def run(
                         )
             except subprocess.TimeoutExpired:
                 logging.debug(f"PID {proc.pid} timed out; sending kill.")
+                if is_any_windows():
+                    # Kill the entire process tree before proc.communicate() to
+                    # avoid blocking indefinitely: grandchild installer
+                    # processes (spawned by e.g. winget) inherit pipe handles
+                    # and keep them open even after proc.kill(), so
+                    # proc.communicate() would block until every grandchild
+                    # exits on its own.
+                    subprocess.run(
+                        ("taskkill", "/F", "/T", "/PID", str(proc.pid)),
+                        capture_output=True,
+                        timeout=10,
+                    )
+                    for proc_name in self.windows_processes_to_cleanup:
+                        subprocess.run(
+                            ("taskkill", "/F", "/IM", proc_name),
+                            capture_output=True,
+                            timeout=5,
+                        )
                 proc.kill()
                 stdout, stderr = proc.communicate()
                 logging.debug(f"PID {proc.pid} killed; exit {proc.returncode}.")