feat(polls): implement group trip polling MVP

Add complete group trip polling feature allowing users to share trips
with friends for voting using Borda count scoring.

New components:
- TripPoll and PollVote domain models with share codes and rankings
- LocalTripPoll and LocalPollVote SwiftData models for persistence
- CKTripPoll and CKPollVote CloudKit record wrappers
- PollService actor for CloudKit CRUD operations and subscriptions
- PollCreation/Detail/Voting views and view models
- Deep link handling for sportstime://poll/{code} URLs
- Debug Pro status override toggle in Settings

Integration:
- HomeView shows polls section in My Trips
- SportsTimeApp registers SwiftData models and handles deep links

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SportsTime/Features/Settings/Views/SettingsView.swift

@@ -260,6 +260,13 @@ struct SettingsView: View {
     #if DEBUG
     private var debugSection: some View {
         Section {
+            Toggle(isOn: Binding(
+                get: { StoreManager.shared.debugProOverride },
+                set: { StoreManager.shared.debugProOverride = $0 }
+            )) {
+                Label("Override Pro Status", systemImage: "star.fill")
+            }
+
             Button {
                 showOnboardingPaywall = true
             } label: {