feat: add health check endpoint and update Makefile for health URL

internal/handlers/api/health_handler.go

@@ -0,0 +1,15 @@
+package api
+
+import (
+	"agent-desk/internal/pkg/httpx"
+
+	"github.com/gin-gonic/gin"
+)
+
+type healthResponse struct {
+	Status string `json:"status"`
+}
+
+func Health(ctx *gin.Context) {
+	httpx.WriteJSON(ctx, &healthResponse{Status: "ok"})
+}