Set pin a11y improvements

ElementX/Sources/Screens/AppLock/AppLockSetupPINScreen/View/AppLockSetupPINScreen.swift

@@ -66,6 +66,7 @@ struct AppLockSetupPINScreen: View {
                 .font(.compound.headingMDBold)
                 .multilineTextAlignment(.center)
                 .foregroundColor(.compound.textPrimary)
+                .accessibilityAddTraits(.isHeader)
             
             Text(context.viewState.subtitle)
                 .font(.compound.bodyMD)

ElementX/Sources/Screens/AppLock/AppLockSetupPINScreen/View/PINTextField.swift

@@ -20,6 +20,8 @@ struct PINTextField: View {
         textField
             .textFieldStyle(PINTextFieldStyle(pinCode: pinCode, isSecure: isSecure, maxLength: maxLength, size: size))
             .keyboardType(.numberPad)
+            // Keep the label persistent: the field's title behaves as a placeholder and is only announced while empty.
+            .accessibilityLabel(L10n.a11yPinField)
             .accessibilityIdentifier(A11yIdentifiers.appLockSetupPINScreen.textField)
             .onChange(of: pinCode) { _, newValue in
                 let sanitized = sanitize(newValue)