refactor(core): decouple gin from pkg/util and reduce code duplication

backend/core/extpoints/registry.go

@@ -0,0 +1,22 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package extpoints
+
+import (
+	"slices"
+	"sync"
+)
+
+func unregisterEntry[T any](mu *sync.RWMutex, lookup map[string]T, list *[]T, key string, matches func(T) bool) bool {
+	mu.Lock()
+	defer mu.Unlock()
+
+	if _, exists := lookup[key]; !exists {
+		return false
+	}
+
+	delete(lookup, key)
+	*list = slices.DeleteFunc(*list, matches)
+	return true
+}