fix: resolve compiler warnings across codebase

- PaywallView: remove unnecessary nil coalescing for currencyCode
- GameDAGRouter: change var to let for immutable compositeKeys
- GamesHistoryRow/View: add missing wnba and nwsl switch cases
- VisitDetailView: fix unused variable in preview
- AchievementEngine: use convenience init to avoid default parameter warning
- ProgressCardGenerator: use method overload instead of default parameter
- StadiumProximityMatcher: extract constants to ProximityConstants enum

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

SportsTime/Export/Services/ProgressCardGenerator.swift

@@ -21,6 +21,13 @@ final class ProgressCardGenerator {
 
     // MARK: - Generate Card
 
+    /// Generate a shareable progress card image with default options
+    /// - Parameter progress: The league progress data
+    /// - Returns: The generated UIImage
+    func generateCard(progress: LeagueProgress) async throws -> UIImage {
+        try await generateCard(progress: progress, options: ProgressCardOptions())
+    }
+
     /// Generate a shareable progress card image
     /// - Parameters:
     ///   - progress: The league progress data
@@ -28,7 +35,7 @@ final class ProgressCardGenerator {
     /// - Returns: The generated UIImage
     func generateCard(
         progress: LeagueProgress,
-        options: ProgressCardOptions = ProgressCardOptions()
+        options: ProgressCardOptions
     ) async throws -> UIImage {
         // Generate map snapshot if needed
         var mapSnapshot: UIImage?