perf: lazy hierarchical loading for game picker

Replace upfront loading of all games with lazy Sport → Team → Game
hierarchy. Games are now fetched per-team when expanded and cached
to prevent re-fetching. Also removes pagination workaround and
pre-computes groupings in ScheduleViewModel to avoid per-render work.

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

SportsTime/Core/Services/DataProvider.swift

@@ -219,6 +219,37 @@ final class AppDataProvider: ObservableObject {
         }
         return RichGame(game: game, homeTeam: homeTeam, awayTeam: awayTeam, stadium: stadium)
     }
+
+    /// Get all games for a specific team (home or away) - for lazy loading in game picker
+    func gamesForTeam(teamId: String) async throws -> [RichGame] {
+        guard let context = modelContext else {
+            throw DataProviderError.contextNotConfigured
+        }
+
+        // Fetch all non-deprecated games (predicate with captured vars causes type-check timeout)
+        let descriptor = FetchDescriptor<CanonicalGame>(
+            predicate: #Predicate<CanonicalGame> { $0.deprecatedAt == nil },
+            sortBy: [SortDescriptor(\.dateTime)]
+        )
+
+        let allCanonical: [CanonicalGame] = try context.fetch(descriptor)
+
+        // Filter by team in Swift (fast for ~5K games)
+        var teamGames: [RichGame] = []
+        for canonical in allCanonical {
+            guard canonical.homeTeamCanonicalId == teamId || canonical.awayTeamCanonicalId == teamId else {
+                continue
+            }
+            let game = canonical.toDomain()
+            guard let homeTeam = teamsById[game.homeTeamId],
+                  let awayTeam = teamsById[game.awayTeamId],
+                  let stadium = stadiumsById[game.stadiumId] else {
+                continue
+            }
+            teamGames.append(RichGame(game: game, homeTeam: homeTeam, awayTeam: awayTeam, stadium: stadium))
+        }
+        return teamGames
+    }
 }
 
 // MARK: - Errors