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/Schedule/ViewModels/ScheduleViewModel.swift

@@ -111,6 +111,7 @@ final class ScheduleViewModel {
 
             self.diagnostics = newDiagnostics
 
+            AnalyticsManager.shared.track(.scheduleViewed(sports: Array(selectedSports).map(\.rawValue)))
             logger.info("📅 Returned \(self.games.count) games")
             for (sport, count) in sportCounts.sorted(by: { $0.key.rawValue < $1.key.rawValue }) {
                 logger.info("📅   \(sport.rawValue): \(count) games")
@@ -149,6 +150,7 @@ final class ScheduleViewModel {
         } else {
             selectedSports.insert(sport)
         }
+        AnalyticsManager.shared.track(.scheduleFiltered(sport: sport.rawValue, dateRange: "\(startDate.formatted(.dateTime.month().day())) - \(endDate.formatted(.dateTime.month().day()))"))
         Task {
             await loadGames()
         }