.wslconfig option to cleanly shutdown long-running WSL processes on Windows shutdown

Is your feature request related to a problem? Please describe.

When Windows shuts down, WSL is abruptly terminated. If you have long-running processes (systemd, servers, or just long jobs) running in WSL at the time that Windows shuts down, these processes do not get a chance to exit cleanly. While this can be worked around by manually terminating these processes when the Windows shutdown is user-initiated, it is obviously more of a problem for automatic shutdowns due to update installs, etc.

Describe the solution you'd like
I would like an option to be provided in .wslconfig or wsl.conf to specify a command/script to be executed inside WSL/a particular WSL distro when Windows shutdown runs, and which will delay the continuation of Windows shutdown until such time as the command/script returns, indicating that long-running processes inside WSL have been shut down cleanly.

The issue names .wslconfig and wsl.conf but no source files, tests, or entry points. Start by reviewing how those configuration files are documented and handled, then trace the WSL and Windows shutdown lifecycle. Done would require a defined configuration format and verified clean shutdown behavior for targeted distributions.