Update paywall headline to a single line.

Keep the premium upgrade title on one line for cleaner visual hierarchy and consistency in the paywall header.

Made-with: Cursor

google_apps/PremiumFeaturesView.swift

@@ -93,7 +93,7 @@ struct PremiumFeaturesView: View {
                         .disabled(premiumStore.purchaseInProgress)
                     }
 
-                    Text("Upgrade to unlock all\nPremium Features")
+                    Text("Upgrade to unlock all Premium Features")
                         .font(.system(size: 20, weight: .bold))
                         .foregroundStyle(primaryTextColor)
                         .lineSpacing(1)