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/PollVotingViewModel.swift

@@ -0,0 +1,90 @@
+//
+//  PollVotingViewModel.swift
+//  SportsTime
+//
+//  ViewModel for voting on trip polls
+//
+
+import Foundation
+import SwiftUI
+
+@Observable
+@MainActor
+final class PollVotingViewModel {
+    var rankings: [Int] = []  // Trip indices in preference order
+    var isLoading = false
+    var error: PollError?
+    var didSubmit = false
+
+    private let pollService = PollService.shared
+
+    var canSubmit: Bool {
+        !rankings.isEmpty
+    }
+
+    func initializeRankings(tripCount: Int, existingVote: PollVote?) {
+        if let vote = existingVote {
+            rankings = vote.rankings
+        } else {
+            // Default: trips in original order
+            rankings = Array(0..<tripCount)
+        }
+    }
+
+    func moveTrip(from source: IndexSet, to destination: Int) {
+        rankings.move(fromOffsets: source, toOffset: destination)
+    }
+
+    func submitVote(pollId: UUID) async {
+        guard canSubmit else { return }
+
+        isLoading = true
+        error = nil
+
+        do {
+            let userId = try await pollService.getCurrentUserRecordID()
+
+            let vote = PollVote(
+                pollId: pollId,
+                odg: userId,
+                rankings: rankings
+            )
+
+            _ = try await pollService.submitVote(vote)
+            didSubmit = true
+        } catch let pollError as PollError {
+            error = pollError
+        } catch {
+            self.error = .unknown(error)
+        }
+
+        isLoading = false
+    }
+
+    func updateVote(existingVote: PollVote) async {
+        guard canSubmit else { return }
+
+        isLoading = true
+        error = nil
+
+        do {
+            var updatedVote = existingVote
+            updatedVote.rankings = rankings
+
+            _ = try await pollService.updateVote(updatedVote)
+            didSubmit = true
+        } catch let pollError as PollError {
+            error = pollError
+        } catch {
+            self.error = .unknown(error)
+        }
+
+        isLoading = false
+    }
+
+    func reset() {
+        rankings = []
+        error = nil
+        didSubmit = false
+    }
+}