feat: add PostHog analytics with full event tracking across app

Integrate self-hosted PostHog (SPM) with AnalyticsManager singleton wrapping
all SDK calls. Adds ~40 type-safe events covering trip planning, schedule,
progress, IAP, settings, polls, export, and share flows. Includes session
replay, autocapture, network telemetry, privacy opt-out toggle in Settings,
and super properties (app version, device, pro status, selected sports).

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

SportsTime/Features/Progress/ViewModels/ProgressViewModel.swift

@@ -176,6 +176,7 @@ final class ProgressViewModel {
 
     func selectSport(_ sport: Sport) {
         selectedSport = sport
+        AnalyticsManager.shared.track(.sportSwitched(sport: sport.rawValue))
     }
 
     func clearError() {
@@ -188,6 +189,10 @@ final class ProgressViewModel {
     func deleteVisit(_ visit: StadiumVisit) async throws {
         guard let container = modelContainer else { return }
 
+        if let sport = visit.sportEnum {
+            AnalyticsManager.shared.track(.stadiumVisitDeleted(stadiumId: visit.stadiumId, sport: sport.rawValue))
+        }
+
         let context = ModelContext(container)
         context.delete(visit)
         try context.save()