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/Settings/ViewModels/SettingsViewModel.swift

@@ -14,7 +14,9 @@ final class SettingsViewModel {
 
     var selectedTheme: AppTheme {
         didSet {
+            let oldName = oldValue.displayName
             ThemeManager.shared.currentTheme = selectedTheme
+            AnalyticsManager.shared.track(.themeChanged(from: oldName, to: selectedTheme.displayName))
         }
     }
 
@@ -23,7 +25,10 @@ final class SettingsViewModel {
     }
 
     var maxDrivingHoursPerDay: Int {
-        didSet { savePreferences() }
+        didSet {
+            savePreferences()
+            AnalyticsManager.shared.track(.drivingHoursChanged(hours: maxDrivingHoursPerDay))
+        }
     }
 
     // MARK: - App Info
@@ -63,8 +68,10 @@ final class SettingsViewModel {
             // Don't allow removing all sports
             guard selectedSports.count > 1 else { return }
             selectedSports.remove(sport)
+            AnalyticsManager.shared.track(.sportToggled(sport: sport.rawValue, enabled: false))
         } else {
             selectedSports.insert(sport)
+            AnalyticsManager.shared.track(.sportToggled(sport: sport.rawValue, enabled: true))
         }
     }
 
@@ -73,6 +80,7 @@ final class SettingsViewModel {
         selectedSports = Set(Sport.supported)
         maxDrivingHoursPerDay = 8
         AppearanceManager.shared.currentMode = .system
+        AnalyticsManager.shared.track(.settingsReset)
     }
 
     // MARK: - Persistence