refactor (appwide): switch project structure to feature-first structure

[ahmedtohamy1]

• also do minor cleanups
• commonize common components

The feature-first approach demands that we create a new folder for every new feature that we add to our app. And inside that folder, we can add the layers themselves as sub-folders. I find this approach more logical because we can easily see all the files that belong to a certain feature, grouped by layer.

[ahmedtohamy1]

Notes:

1. if i got more free time i may rewrite entire app in modern statemanagment approuch like BloC/Riverpod
2. switch to isar db instead of current impl
3. add external datasource with supabase