feat: check endpoint for CORS applications

stubs.go

@@ -8,6 +8,7 @@ import (
 func startStubs(r *gin.Engine) {
 	r.GET("/auth/v2/login", stubsHandler)
 	r.GET("/auth/v2/verify", stubsHandler)
+	r.GET("/auth/v2/check", EnsureLogin(false), func(ctx *gin.Context) { ctx.JSON(200, gin.H{"success": "true"}) })
 }
 
 func stubsHandler(c *gin.Context) {