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/types.ts

@@ -8,7 +8,7 @@ import {
 } from "express";
 import type { MatchFunction } from "path-to-regexp";
 import { z } from "zod";
-import type { SessionData } from "./auth/types";
+import type { Session } from "./auth/types";
 import { type ContentType, contentTypes } from "./content-types";
 import { type HttpCode, httpCodes } from "./http-codes";
 import {
@@ -40,7 +40,7 @@ export type Call = {
     parameters: object;
     request: ExpressRequest;
     user: MaybeUser;
-    session: SessionData | null;
+    session: Session;
 };
 
 export type InternalHandler = (req: ExpressRequest) => Promise<Result>;