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/OAuthModels.swift

@@ -0,0 +1,43 @@
+//
+//  OAuthModels.swift
+//  FantasyWatch
+//
+//  Created by Claude Code
+//
+
+import Foundation
+
+struct TokenPair: Codable, Equatable, Sendable {
+    let accessToken: String
+    let refreshToken: String
+    let expiresIn: Int
+    let tokenType: String
+
+    var expiryDate: Date {
+        Date().addingTimeInterval(TimeInterval(expiresIn))
+    }
+}
+
+struct OAuthTokenResponse: Codable {
+    let access_token: String
+    let refresh_token: String
+    let expires_in: Int
+    let token_type: String
+
+    func toTokenPair() -> TokenPair {
+        TokenPair(
+            accessToken: access_token,
+            refreshToken: refresh_token,
+            expiresIn: expires_in,
+            tokenType: token_type
+        )
+    }
+}
+
+enum OAuthError: Error, Equatable {
+    case noRefreshToken
+    case tokenExpired
+    case authorizationFailed
+    case networkError(String)
+    case invalidResponse
+}