Add admin UI

internal/admin/response.go

@@ -0,0 +1,45 @@
+package admin
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// APIResponse is the standard JSON response wrapper.
+type APIResponse struct {
+	Success bool        `json:"success"`
+	Data    interface{} `json:"data,omitempty"`
+	Error   *APIError   `json:"error,omitempty"`
+}
+
+// APIError represents an error response.
+type APIError struct {
+	Code    string `json:"code"`
+	Message string `json:"message"`
+}
+
+// writeJSON writes a JSON response.
+func writeJSON(w http.ResponseWriter, statusCode int, data interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(statusCode)
+	json.NewEncoder(w).Encode(data)
+}
+
+// writeSuccess writes a successful JSON response.
+func writeSuccess(w http.ResponseWriter, data interface{}) {
+	writeJSON(w, http.StatusOK, APIResponse{
+		Success: true,
+		Data:    data,
+	})
+}
+
+// writeError writes an error JSON response.
+func writeError(w http.ResponseWriter, statusCode int, code, message string) {
+	writeJSON(w, statusCode, APIResponse{
+		Success: false,
+		Error: &APIError{
+			Code:    code,
+			Message: message,
+		},
+	})
+}