small fix, don't worry about it

backend/internal/api/handlers/placeholder_handler.go

@@ -0,0 +1,22 @@
+package handlers
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+type PlaceholderHandler struct{}
+
+func NewPlaceholderHandler() *PlaceholderHandler {
+	return &PlaceholderHandler{}
+}
+
+func (h *PlaceholderHandler) NotImplemented(feature string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		c.JSON(http.StatusNotImplemented, gin.H{
+			"error":   "not implemented",
+			"feature": feature,
+		})
+	}
+}