SwitchView: check the VoiceOver traits (only .isToggle, no button trait) #27

Summary

SwitchView (Components/Switch/SwitchView.swift) is an onTapGesture shape, not a Button or Toggle. Its only accessibility trait is .isToggle, and it sets an accessibilityValue of "On"/"Off" by hand.

This was found while reviewing #15 and is not a regression. iOS 17+ already ran this path, and #15 only removed the .isButton fallback for iOS 14–16.

Risk (not verified on a device)

• The element has no button trait, so VoiceOver may not give the activation hint ("double-tap to toggle").
• The state may be announced twice, once from accessibilityValue and once from the toggle trait.

Proposed fix

1. Run VoiceOver against a native Toggle and SwitchView side by side.
2. Then pick one:
   • accessibilityAddTraits([.isButton, .isToggle]), keeping or dropping the manual value depending on what VoiceOver reads;
   • or build the switch as a Toggle with a custom ToggleStyle, so it gets the system semantics for free.

Related: the accessibility audit of the shared components (ticket 32072).