Quitting the desktop app now shuts down the daemon it started, so
"restart the app" is a complete reset users can act on without first
learning what a daemon is. The old default kept it alive; the toggle
under Settings > Host still opts back in.
Existing installs already persisted `keepRunningAfterQuit: true` from
the old default, so a new default alone would only reach fresh installs.
A one-time migration resets it, and an explicit toggle afterwards
persists the migration flag and is never overridden again.
Only a desktop-managed daemon is stopped — one started with
`paseo daemon start` is left alone.
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