Revert "home: debounce last notified"
This is technically incorrect, as debouncing can prevent saving
important events.
The proper way to do this is to save it locally in memory, and then
debouncing the saving itself. Will do this soon.
Reverts: a9b4cfd424
Fixes: https://github.com/damus-io/damus/issues/1439
Changelog-Fixed: Fixed old notifications always appearing on first start
1a2ac976a3