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/ScenarioPlanner.swift

@@ -23,7 +23,7 @@ enum ScenarioPlannerFactory {
     /// Creates the appropriate planner based on the request inputs
     static func planner(for request: PlanningRequest) -> ScenarioPlanner {
         print("🔍 ScenarioPlannerFactory: Selecting planner...")
-        print("   - followTeamId: \(request.preferences.followTeamId?.uuidString ?? "nil")")
+        print("   - followTeamId: \(request.preferences.followTeamId ?? "nil")")
         print("   - selectedGames.count: \(request.selectedGames.count)")
         print("   - startLocation: \(request.startLocation?.name ?? "nil")")
         print("   - endLocation: \(request.endLocation?.name ?? "nil")")