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/Features/Progress/ViewModels/PhotoImportViewModel.swift

@@ -174,12 +174,14 @@ final class PhotoImportViewModel {
 
             // Create the visit
             let visit = StadiumVisit(
-                canonicalStadiumId: match.stadium.id.uuidString,
-                stadiumUUID: match.stadium.id,
+                stadiumId: match.stadium.id,
                 stadiumNameAtVisit: match.stadium.name,
                 visitDate: match.game.dateTime,
                 sport: match.game.sport,
                 visitType: .game,
+                gameId: match.game.id,
+                homeTeamId: match.homeTeam.id,
+                awayTeamId: match.awayTeam.id,
                 homeTeamName: match.homeTeam.fullName,
                 awayTeamName: match.awayTeam.fullName,
                 finalScore: match.formattedFinalScore,