fix: move paywall sheet to stable scope and fix map button positions

Move .sheet(isPresented: $showPaywall) from subscription section to
top-level body so StoreManager state changes don't dismiss the sheet.
Reposition heart (16pt top/trailing) and map (16pt bottom/trailing,
above gradient) buttons on trip detail map.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

SportsTime/Features/Settings/Views/SettingsView.swift

@@ -76,6 +76,9 @@ struct SettingsView: View {
         } message: {
             Text("This will reset all settings to their default values.")
         }
+        .sheet(isPresented: $showPaywall) {
+            PaywallView(source: "settings")
+        }
         .sheet(isPresented: $showOnboardingPaywall) {
             OnboardingPaywallView(isPresented: $showOnboardingPaywall)
         }
@@ -814,9 +817,6 @@ struct SettingsView: View {
             Text("Subscription")
         }
         .listRowBackground(Theme.cardBackground(colorScheme))
-        .sheet(isPresented: $showPaywall) {
-            PaywallView(source: "settings")
-        }
     }
 
     // MARK: - Helpers