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/Polls/ViewModels/PollCreationViewModel.swift

@@ -0,0 +1,77 @@
+//
+//  PollCreationViewModel.swift
+//  SportsTime
+//
+//  ViewModel for creating trip polls
+//
+
+import Foundation
+import SwiftUI
+
+@Observable
+@MainActor
+final class PollCreationViewModel {
+    var title: String = ""
+    var selectedTripIds: Set<UUID> = []
+    var isLoading = false
+    var error: PollError?
+    var createdPoll: TripPoll?
+
+    private let pollService = PollService.shared
+
+    var canCreate: Bool {
+        !title.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
+            && selectedTripIds.count >= 2
+    }
+
+    var validationMessage: String? {
+        if title.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
+            return "Enter a title for your poll"
+        }
+        if selectedTripIds.count < 2 {
+            return "Select at least 2 trips to create a poll"
+        }
+        return nil
+    }
+
+    func createPoll(trips: [Trip]) async {
+        guard canCreate else { return }
+
+        isLoading = true
+        error = nil
+
+        do {
+            let userId = try await pollService.getCurrentUserRecordID()
+            let selectedTrips = trips.filter { selectedTripIds.contains($0.id) }
+
+            let poll = TripPoll(
+                title: title.trimmingCharacters(in: .whitespacesAndNewlines),
+                ownerId: userId,
+                tripSnapshots: selectedTrips
+            )
+
+            createdPoll = try await pollService.createPoll(poll)
+        } catch let pollError as PollError {
+            error = pollError
+        } catch {
+            self.error = .unknown(error)
+        }
+
+        isLoading = false
+    }
+
+    func toggleTrip(_ tripId: UUID) {
+        if selectedTripIds.contains(tripId) {
+            selectedTripIds.remove(tripId)
+        } else {
+            selectedTripIds.insert(tripId)
+        }
+    }
+
+    func reset() {
+        title = ""
+        selectedTripIds = []
+        error = nil
+        createdPoll = nil
+    }
+}