Crash on resource modification with multiple resources screens

Steps to reproduce:
1. Open resources screen
2. Select tag
3. Open gallery with this selection
4. Click on tag and then on `Navigate`, a new resources fragment will open
5. Modify a resource from this selection
6. Return to the first resources screen

The problem is that we are using `FragmentResult` to send tag or resource change events. But this event can only be consumed once, so the first resources fragment didn't update the selection and the index has already changed.

A possible solution is to replace the `FragmentResult` with changes flow in `ResourcesIndex` and `TagStorage`

Start by tracing the resources screens and fragments involved in the reproduction, then inspect how FragmentResult events are sent and consumed by ResourcesIndex and TagStorage. Reproduce the sequence with two resources screens and a modified resource; done means both screens retain the correct selection and index without a crash, with coverage for the event flow.

Written by the indexing model from the issue text.