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/utils/format.ts

@@ -0,0 +1,18 @@
+/** Split a comma-separated input into trimmed non-empty parts. */
+export function splitList(text: string): string[] {
+  return text
+    .split(",")
+    .map((s) => s.trim())
+    .filter(Boolean);
+}
+
+/** Comma-separated filter match → single value, list, or null when empty. */
+export function parseMatch(text: string): string | string[] | null {
+  const parts = splitList(text);
+  if (!parts.length) return null;
+  return parts.length === 1 ? parts[0]! : parts;
+}
+
+export function fmtTime(ts: number): string {
+  return new Date(ts).toLocaleString();
+}