Update tui error handling

- Allow each view to position error banners where they choose
- Add global 'esc' key handler to dismiss errors

pkg/tui/shared/shared.go

@@ -13,7 +13,7 @@ type ViewModel interface {
 	// View methods
 	Header(width int) string
 	// Render the view's main content into a container of the given dimensions
-	Content(width, height int) string
+	Content(width, height int, errors string) string
 	Footer(width int) string
 }