Merge follow/unfollow from kernel

Jakub Gladysz (1):
      ui: add follow button

kernelkind (14):
      bump nostrdb
      move polling responsibility to `AccountData`
      `AccountData`: decouple query from constructor
      add constructor for `AccountData`
      add `Contacts`
      use `Contacts` in `AccountData`
      expose `AccountSubs`
      Unify sub for contacts in accounts & timeline
      move `styled_button_toggleable` to notedeck_ui
      construct NoteBuilder from existing note
      send kind 3 event
      add actions for follow/unfollow
      add UI for (un)follow
      send contact list event on account creation

crates/notedeck_columns/src/ui/timeline.rs

@@ -154,6 +154,9 @@ fn timeline_ui(
             error!("tried to render timeline in column, but timeline was missing");
             // TODO (jb55): render error when timeline is missing?
             // this shouldn't happen...
+            //
+            // NOTE (jb55): it can easily happen if you add a timeline column without calling
+            // add_new_timeline_column, since that sets up the initial subs, etc
             return None;
         };