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/ProgressViewModel.swift

@@ -41,10 +41,10 @@ final class ProgressViewModel {
         let visitedStadiumIds = Set(
             visits
                 .filter { $0.sportEnum == selectedSport }
-                .compactMap { visit -> UUID? in
+                .compactMap { visit -> String? in
                     // Match visit's canonical stadium ID to a stadium
                     stadiums.first { stadium in
-                        stadium.id == visit.stadiumUUID
+                        stadium.id == visit.stadiumId
                     }?.id
                 }
         )
@@ -62,11 +62,11 @@ final class ProgressViewModel {
     }
 
     /// Stadium visit status indexed by stadium ID
-    var stadiumVisitStatus: [UUID: StadiumVisitStatus] {
-        var statusMap: [UUID: StadiumVisitStatus] = [:]
+    var stadiumVisitStatus: [String: StadiumVisitStatus] {
+        var statusMap: [String: StadiumVisitStatus] = [:]
 
         // Group visits by stadium
-        let visitsByStadium = Dictionary(grouping: visits.filter { $0.sportEnum == selectedSport }) { $0.stadiumUUID }
+        let visitsByStadium = Dictionary(grouping: visits.filter { $0.sportEnum == selectedSport }) { $0.stadiumId }
 
         for stadium in stadiums {
             if let stadiumVisits = visitsByStadium[stadium.id], !stadiumVisits.isEmpty {
@@ -114,7 +114,7 @@ final class ProgressViewModel {
             .sorted { $0.visitDate > $1.visitDate }
             .prefix(10)
             .compactMap { visit -> VisitSummary? in
-                guard let stadium = stadiums.first(where: { $0.id == visit.stadiumUUID }),
+                guard let stadium = stadiums.first(where: { $0.id == visit.stadiumId }),
                       let sport = visit.sportEnum else {
                     return nil
                 }