iOS: Duo layout fixes, swipe-up option, fuller backup restore

- DuoRail sits at the bottom of the strip, clear of the back buttons
- Setting to turn off swipe up for Playing Next
- Tighter Now Playing on iPhone Duo (folded and docked), regular phones unchanged
- Bigger stacked stem faders in the Duo deck
- Backup v2 restores song mixes, custom presets and stem playlist covers

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

ios/Stemify/UI/Screens/NowPlayingOptions.swift

@@ -50,6 +50,18 @@ struct NowPlayingOptionsScreen: View {
                     .themedRow()
                 }
             } footer: { Text("Choose which buttons show under the playback controls.").foregroundStyle(p.label2) }
+            Section {
+                Toggle(isOn: $s.swipeUpQueue) {
+                    HStack(spacing: 14) {
+                        SettingsIcon(symbol: "hand.draw", bg: 0x5856D6)
+                        Text("Swipe Up for Playing Next").foregroundStyle(p.label)
+                    }
+                }
+                .tint(Color(hex: 0x34C759))
+                .themedRow()
+            } header: { Text("Gestures").foregroundStyle(p.label2) } footer: {
+                Text("Off, swiping up on the art or the stems does nothing. Tap Playing Next under the controls instead.").foregroundStyle(p.label2)
+            }
             Section {
                 Toggle(isOn: $s.lockScreenMix) {
                     HStack(spacing: 14) {