feat: implement auth middleware using domain service

internal/auth/middleware/middleware.go

@@ -0,0 +1,20 @@
+package middleware
+
+import (
+	"mal/internal/domain"
+
+	"github.com/gin-gonic/gin"
+)
+
+func AuthMiddleware(svc domain.AuthService) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		sessionID, err := c.Cookie("session_id")
+		if err == nil {
+			user, err := svc.ValidateSession(c.Request.Context(), sessionID)
+			if err == nil {
+				c.Set("User", user)
+			}
+		}
+		c.Next()
+	}
+}