[feature] Notifications / Reactions refactor

Currently the notifications experience feels a bit disconnected

And the big thing is that one watch can only have one notification body/title, it would be way cooler to have multiple notifications for one watch, or one watch group

and that brings me to the point of, they arent always just notifications, but sometimes they are more 'reactions', like for example i want to send a tweet or something

So lets rename `notifications` to `Reactions`


No files, tests, or entry points are identified; start by mapping the existing notifications and watch-group flow and reviewing the issue's example image. Done requires an agreed design and implementation for multiple reactions per watch or group, including the proposed rename from notifications to Reactions.

Written by the indexing model from the issue text.