Fix game times with UTC data, restructure schedule by date

- Update games_canonical.json to use ISO 8601 UTC timestamps (game_datetime_utc)
- Fix BootstrapService timezone-aware parsing for venue-local fallback
- Fix thread-unsafe shared DateFormatter in RichGame local time display
- Bump SchemaVersion to 4 to force re-bootstrap with correct UTC data
- Restructure schedule view: group by date instead of sport, with sport
  icons on each row and date section headers showing game counts
- Fix schedule row backgrounds using Theme.cardBackground instead of black
- Sort games by UTC time with local-time tiebreaker for same-instant games

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

SportsTime/Features/Schedule/ViewModels/ScheduleViewModel.swift

@@ -32,8 +32,8 @@ final class ScheduleViewModel {
 
     // MARK: - Pre-computed Groupings (avoid computed property overhead)
 
-    /// Games grouped by sport - pre-computed to avoid re-grouping on every render
-    private(set) var gamesBySport: [(sport: Sport, games: [RichGame])] = []
+    /// Games grouped by date - pre-computed to avoid re-grouping on every render
+    private(set) var gamesByDate: [(date: Date, games: [RichGame])] = []
 
     /// All games matching current filters (before any display limiting)
     private var filteredGames: [RichGame] = []
@@ -193,15 +193,20 @@ final class ScheduleViewModel {
             }
         }
 
-        // Step 2: Pre-compute grouping by sport (done once, not per-render)
-        let grouped = Dictionary(grouping: filteredGames) { $0.game.sport }
-        gamesBySport = grouped
-            .sorted { lhs, rhs in
-                let lhsIndex = Sport.allCases.firstIndex(of: lhs.key) ?? 0
-                let rhsIndex = Sport.allCases.firstIndex(of: rhs.key) ?? 0
-                return lhsIndex < rhsIndex
-            }
-            .map { (sport: $0.key, games: $0.value.sorted { $0.game.dateTime < $1.game.dateTime }) }
+        // Step 2: Pre-compute grouping by date (done once, not per-render)
+        let calendar = Calendar.current
+        let grouped = Dictionary(grouping: filteredGames) { calendar.startOfDay(for: $0.game.dateTime) }
+        gamesByDate = grouped
+            .sorted { $0.key < $1.key }
+            .map { (date: $0.key, games: $0.value.sorted { lhs, rhs in
+                if lhs.game.dateTime == rhs.game.dateTime {
+                    // Same UTC time: sort by local display time (earlier local times first)
+                    let lhsOffset = lhs.stadium.timeZone?.secondsFromGMT(for: lhs.game.dateTime) ?? 0
+                    let rhsOffset = rhs.stadium.timeZone?.secondsFromGMT(for: rhs.game.dateTime) ?? 0
+                    return lhsOffset < rhsOffset
+                }
+                return lhs.game.dateTime < rhs.game.dateTime
+            }) }
     }
 }