refactor(admin): unify webui fetch/copy/format helpers; fix audit tab load and delete-group count

- apiFetch + shared needLogin (any 401 shows the login card) replaces six
  duplicated fetch/401/error-handling blocks in the admin composables
- useCopy composable: clipboard + execCommand fallback with timed reset,
  used by MembersPanel and WebhookPanel
- utils/format.ts (fmtTime/splitList/parseMatch) removes inline duplicates
  across SendLogs, AuditLog, RouteEditor and GroupEditor
- fix: load the audit log when the audit tab becomes active (client-side
  navigation never remounted the page, leaving the list empty on first visit)
- fix: fetch the real route count for a group before confirming deletion
  instead of reusing the currently open group's route list

app/components/GroupEditor.vue

@@ -216,13 +216,6 @@ const form = reactive({
   logTopicId: "",
 });
 
-function splitList(text: string): string[] {
-  return text
-    .split(",")
-    .map((s) => s.trim())
-    .filter(Boolean);
-}
-
 function toggleProvider(p: "github" | "gitea", e: Event): void {
   const checked = (e.target as HTMLInputElement).checked;
   form.providers = checked