feat: nicer smart filters & folders theme (#795)

* fix: color add button and drop

* fix: color scrollbars

* fix: remove infinite scroll and fix scrollbars

* fix: plus icon center

* fix: navigation padding, structure simplif and naming

* fix: simplify scrollbars

* fix: scroll bar simplif + scheme in macos

* fix: magic variables to const

* refactor: extract panel ref state

* refactor: remove dead code, simple macos theme

app/assets/stylesheets/index.css.scss

@@ -2,7 +2,7 @@
 @import 'main';
 @import 'ui';
 @import 'footer';
-@import 'tags';
+@import 'navigation';
 @import 'notes';
 @import 'editor';
 @import 'menus';