feat(web): choose where the search sits, and controls no longer select text

- settings get a search position (left, center by default, right); the top bar
  is three zones and the suggestions open towards the free space
- buttons, chips, tabs, menu items and the home screen controls are not
  text-selectable, so clicks and double clicks no longer highlight labels

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/api/internal/auth/model.go

@@ -37,6 +37,7 @@ type UIPrefs struct {
 	Theme        *string `json:"theme,omitempty"`
 	WaveVariant  *string `json:"wave_variant,omitempty"`
 	WebPlayer    *string `json:"web_player,omitempty"`
+	SearchPos    *string `json:"search_position,omitempty"`
 	MobilePlayer *string `json:"mobile_player,omitempty"`
 	Ambient      *bool   `json:"ambient,omitempty"`
 	CrossfadeS   *int    `json:"crossfade_s,omitempty"`