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/composables/useCopy.ts

@@ -0,0 +1,33 @@
+/**
+ * Clipboard helper with execCommand fallback and a "just copied" flag keyed
+ * by whatever identifies the copied value (a token, "url", "secret", ...).
+ * The flag resets after `duration` ms.
+ */
+export function useCopy(duration = 1500) {
+  const copied = ref("");
+
+  async function copy(text: string, key: string): Promise<void> {
+    try {
+      await navigator.clipboard.writeText(text);
+    } catch {
+      try {
+        const ta = document.createElement("textarea");
+        ta.value = text;
+        ta.style.position = "fixed";
+        ta.style.opacity = "0";
+        document.body.appendChild(ta);
+        ta.select();
+        document.execCommand("copy");
+        document.body.removeChild(ta);
+      } catch {
+        return;
+      }
+    }
+    copied.value = key;
+    window.setTimeout(() => {
+      if (copied.value === key) copied.value = "";
+    }, duration);
+  }
+
+  return { copied, copy };
+}