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/setup.go

@@ -0,0 +1,28 @@
+// 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 (
+    "go.uber.org/fx"
+)
+
+var Module = fx.Module("validation",
+    fx.Provide(
+			NewValidator,
+    ),
+)