refactor/fix: now using pgx errors for postgres error checking instead of trying to look up the error code;

feat: implemented working custom validation;
fix: authservice begin/complete registration

backend/internal/validation/validator.go

@@ -0,0 +1,32 @@
+// Copyright (c) 2025 Nikolai Papin
+//
+// This file is part of Easywish
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+// the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package validation
+
+import (
+	"github.com/go-playground/validator/v10"
+)
+
+func NewValidator() *validator.Validate {
+	v := validator.New()
+
+	for _, handler := range GetCustomHandlers() {
+		v.RegisterValidation(handler.FieldName, handler.Function)
+	}
+
+	return v
+}