add mosis-portal Go project with package signing and validation

portal/internal/api/handlers/handlers.go

@@ -0,0 +1,35 @@
+// Package handlers contains HTTP request handlers
+package handlers
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// ErrorResponse represents an API error response
+type ErrorResponse struct {
+	Error   string `json:"error"`
+	Message string `json:"message,omitempty"`
+}
+
+// NotImplemented returns a 501 Not Implemented response
+func NotImplemented(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusNotImplemented)
+	json.NewEncoder(w).Encode(ErrorResponse{
+		Error:   "not_implemented",
+		Message: "This endpoint is not yet implemented",
+	})
+}
+
+// JSON writes a JSON response with the given status code
+func JSON(w http.ResponseWriter, status int, data interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(data)
+}
+
+// Error writes a JSON error response
+func Error(w http.ResponseWriter, status int, err string, message string) {
+	JSON(w, status, ErrorResponse{Error: err, Message: message})
+}