feat: add admin dashboard with usage stats

Co-authored-by: Cursor <cursoragent@cursor.com>

server/src/middleware/auth.ts

@@ -1,5 +1,6 @@
 import type { Request, Response, NextFunction } from 'express'
 import { hasValidReauth, readSessionFromRequest } from '../session.js'
+import { isAdminUserId } from '../adminConfig.js'
 
 export interface AuthedRequest extends Request {
   userId: string
@@ -31,3 +32,21 @@ export function requireReauth(req: Request, res: Response, next: NextFunction):
   ;(req as AuthedRequest).session = session
   next()
 }
+
+export function requireAdmin(req: Request, res: Response, next: NextFunction): void {
+  const session = readSessionFromRequest(req)
+  if (!session) {
+    res.status(401).json({ error: 'Unauthorized: valid session required' })
+    return
+  }
+
+  if (!isAdminUserId(session.userId)) {
+    res.status(403).json({ error: 'Forbidden: admin access required' })
+    return
+  }
+
+  ;(req as AuthedRequest).userId = session.userId
+  ;(req as AuthedRequest).session = session
+  next()
+}
+