Fix remaining search issues

- [ ] Keyboard push's up tab bar, not sure if I want that
- [ ] autoFocus only works on first render of screen (navigation to), probably want to focus the ref in a focus effect instead
- [ ] Empty search preloads which confuses users

Start at the search screen and inspect the keyboard, navigation focus, and empty-search behavior described in the checklist. Clarify the intended tab-bar behavior, reproduce each case, and consider the work complete when the agreed keyboard, focus, and empty-search behavior is consistent.

Written by the indexing model from the issue text.