Describe the bug
Regression: It's impossible to shutdown from an OS signal after startCtx is Done().

To Reproduce

1. Start an fx app
2. Wait startTimeout (default is 15s).
3. Send SIGTERM to the process
4. Nothing will handle the signal and the app will not shut down

Expected behavior
The apps shut down correctly like it did in the previous release.

Additional context
This line starts the goroutine that dispatches os signals.

After the startCtx is Done(), this goroutine exits and thus there's nothing to process OS signals to initiate shutdown.

Replacing the goroutine invocation by go recv.relayer(context.TODO()) fixed the issue for me. The context passed here should not be Done() until the application stops.