UX fixes and updates of the button interaction

[elstua]

Updated the sticky button for starting new record that was created in #4215.

1. Button is copy from the one inside the note. It give opportunity to not only start recording but also add audio or transcript and create new note for it.
2. button has two different states: standart and small for narrow windows or a lot of tabs.
3. Also I took stop button to the same place as this new button. It means user could stop the recording from any other note, button itself become larger and more red.
4. After pressing stop the recorded tab become active if it wasn't. It help to return focus to the note that was recorded before.

a little bit clean the sidebar.
Removed bg to make block consistent with added search field. Added more focus to the note itself
Whole bg for app become bg-neutral-50
changed hover colors for items in sidebar