Add Session class to provide getUser() on call.session

Wraps SessionData and user into a Session class that handlers can use
via call.session.getUser() instead of accessing services directly.

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

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

express/auth/index.ts

@@ -10,4 +10,11 @@ export { hashPassword, verifyPassword } from "./password";
 export { AuthService, type AuthResult } from "./service";
 export { type AuthStore, InMemoryAuthStore } from "./store";
 export { generateToken, hashToken, SESSION_COOKIE_NAME } from "./token";
-export * from "./types";
+export {
+    type AuthMethod,
+    type SessionData,
+    type TokenId,
+    type TokenType,
+    Session,
+    tokenLifetimes,
+} from "./types";