refactor: change domain model IDs from UUID to String canonical IDs

This refactor fixes the achievement system by using stable canonical string
IDs (e.g., "stadium_mlb_fenway_park") instead of random UUIDs. This ensures
stadium mappings for achievements are consistent across app launches and
CloudKit sync operations.

Changes:
- Stadium, Team, Game: id property changed from UUID to String
- Trip, TripStop, TripPreferences: updated to use String IDs for games/stadiums
- CKModels: removed UUID parsing, use canonical IDs directly
- AchievementEngine: now matches against canonical stadium IDs
- All test files updated to use String IDs instead of UUID()

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SportsTime/Planning/Engine/ScenarioBPlanner.swift

@@ -316,7 +316,7 @@ final class ScenarioBPlanner: ScenarioPlanner {
     /// Creates separate stops when visiting the same city with other cities in between.
     private func buildStops(
         from games: [Game],
-        stadiums: [UUID: Stadium]
+        stadiums: [String: Stadium]
     ) -> [ItineraryStop] {
         guard !games.isEmpty else { return [] }
 
@@ -325,7 +325,7 @@ final class ScenarioBPlanner: ScenarioPlanner {
 
         // Group consecutive games at the same stadium
         var stops: [ItineraryStop] = []
-        var currentStadiumId: UUID? = nil
+        var currentStadiumId: String? = nil
         var currentGames: [Game] = []
 
         for game in sortedGames {
@@ -357,8 +357,8 @@ final class ScenarioBPlanner: ScenarioPlanner {
     /// Creates an ItineraryStop from a group of games at the same stadium.
     private func createStop(
         from games: [Game],
-        stadiumId: UUID,
-        stadiums: [UUID: Stadium]
+        stadiumId: String,
+        stadiums: [String: Stadium]
     ) -> ItineraryStop? {
         guard !games.isEmpty else { return nil }
 
@@ -396,8 +396,8 @@ final class ScenarioBPlanner: ScenarioPlanner {
     /// For Scenario B, routes must still contain all anchor games.
     private func findRoutesPerRegion(
         games: [Game],
-        stadiums: [UUID: Stadium],
-        anchorGameIds: Set<UUID>,
+        stadiums: [String: Stadium],
+        anchorGameIds: Set<String>,
         allowRepeatCities: Bool
     ) -> [[Game]] {
         // First, determine which region(s) the anchor games are in
@@ -459,7 +459,7 @@ final class ScenarioBPlanner: ScenarioPlanner {
         var unique: [[Game]] = []
 
         for route in routes {
-            let key = route.map { $0.id.uuidString }.sorted().joined(separator: "-")
+            let key = route.map { $0.id }.sorted().joined(separator: "-")
             if !seen.contains(key) {
                 seen.insert(key)
                 unique.append(route)