Initial implementation of Fantasy Hockey watchOS app

Implemented complete TCA architecture for iOS and watchOS targets:
- Authentication flow (Sign in with Apple + Yahoo OAuth)
- OAuth token management with iCloud Key-Value Storage
- Yahoo Fantasy Sports API client with async/await
- Watch Connectivity for iPhone ↔ Watch data sync
- Complete UI for both iPhone and Watch platforms

Core features:
- Matchup score display
- Category breakdown with win/loss/tie indicators
- Roster status tracking
- Manual refresh functionality
- Persistent data caching on Watch

Technical stack:
- The Composable Architecture for state management
- Swift Concurrency (async/await, actors)
- WatchConnectivity framework
- Sign in with Apple
- OAuth 2.0 authentication flow

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

FantasyWatch/Shared/Networking/OAuth/OAuthTokenStorage.swift

@@ -0,0 +1,59 @@
+//
+//  OAuthTokenStorage.swift
+//  FantasyWatch
+//
+//  Created by Claude Code
+//
+
+import Foundation
+
+actor OAuthTokenStorage {
+    private let ubiquitousStore = NSUbiquitousKeyValueStore.default
+
+    private func accessTokenKey(for userID: String) -> String {
+        "com.fantasyhockey.user.\(userID).yahoo.accessToken"
+    }
+
+    private func refreshTokenKey(for userID: String) -> String {
+        "com.fantasyhockey.user.\(userID).yahoo.refreshToken"
+    }
+
+    private func tokenExpiryKey(for userID: String) -> String {
+        "com.fantasyhockey.user.\(userID).yahoo.tokenExpiry"
+    }
+
+    func saveTokenPair(_ tokenPair: TokenPair, for userID: String) {
+        ubiquitousStore.set(tokenPair.accessToken, forKey: accessTokenKey(for: userID))
+        ubiquitousStore.set(tokenPair.refreshToken, forKey: refreshTokenKey(for: userID))
+        ubiquitousStore.set(tokenPair.expiryDate.timeIntervalSince1970, forKey: tokenExpiryKey(for: userID))
+        ubiquitousStore.synchronize()
+    }
+
+    func getAccessToken(for userID: String) -> String? {
+        ubiquitousStore.string(forKey: accessTokenKey(for: userID))
+    }
+
+    func getRefreshToken(for userID: String) -> String? {
+        ubiquitousStore.string(forKey: refreshTokenKey(for: userID))
+    }
+
+    func getTokenExpiry(for userID: String) -> Date? {
+        let timestamp = ubiquitousStore.double(forKey: tokenExpiryKey(for: userID))
+        guard timestamp > 0 else { return nil }
+        return Date(timeIntervalSince1970: timestamp)
+    }
+
+    func isTokenValid(for userID: String) -> Bool {
+        guard let expiryDate = getTokenExpiry(for: userID) else {
+            return false
+        }
+        return expiryDate > Date().addingTimeInterval(60)
+    }
+
+    func clearTokens(for userID: String) {
+        ubiquitousStore.removeObject(forKey: accessTokenKey(for: userID))
+        ubiquitousStore.removeObject(forKey: refreshTokenKey(for: userID))
+        ubiquitousStore.removeObject(forKey: tokenExpiryKey(for: userID))
+        ubiquitousStore.synchronize()
+    }
+}