feat: fix travel placement bug, add theme-based alternate icons, fix animated background crash

- Fix repeat-city travel placement: use stop indices instead of global city name
  matching so Follow Team trips with repeat cities show travel correctly
- Add TravelPlacement helper and regression tests (7 tests)
- Add alternate app icons for each theme, auto-switch on theme change
- Fix index-out-of-range crash in AnimatedSportsBackground (19 configs, was iterating 20)
- Add marketing video configs, engine, and new video components
- Add docs and data exports

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

SportsTime/Core/Theme/Theme.swift

@@ -34,6 +34,19 @@ enum AppTheme: String, CaseIterable, Identifiable {
         }
     }
 
+    /// The alternate icon name in the asset catalog, or nil for the default (teal).
+    var alternateIconName: String? {
+        switch self {
+        case .teal: return nil
+        case .orbit: return "AppIcon-orbit"
+        case .retro: return "AppIcon-retro"
+        case .clutch: return "AppIcon-clutch"
+        case .monochrome: return "AppIcon-monochrome"
+        case .sunset: return "AppIcon-sunset"
+        case .midnight: return "AppIcon-midnight"
+        }
+    }
+
     var previewColors: [Color] {
         switch self {
         case .teal: return [Color(hex: "4ECDC4"), Color(hex: "1A535C"), Color(hex: "FFE66D")]
@@ -56,9 +69,16 @@ final class ThemeManager {
     var currentTheme: AppTheme {
         didSet {
             UserDefaults.standard.set(currentTheme.rawValue, forKey: "selectedTheme")
+            updateAppIcon(for: currentTheme)
         }
     }
 
+    private func updateAppIcon(for theme: AppTheme) {
+        let iconName = theme.alternateIconName
+        guard UIApplication.shared.alternateIconName != iconName else { return }
+        UIApplication.shared.setAlternateIconName(iconName)
+    }
+
     private init() {
         if let saved = UserDefaults.standard.string(forKey: "selectedTheme"),
            let theme = AppTheme(rawValue: saved) {