feat: add permanent deletion for revoked keys

DELETE /admin/api/keys/{id}/purge removes the key record; it requires the key to be revoked first and keeps historical logs. The keys page swaps the revoke button for a delete button once a key is revoked.

web/src/pages/Keys.tsx

@@ -71,7 +71,16 @@ export function KeysPage({ keys, stats, channels, timezone, busy, error, notice,
     action(async () => {
       await api('/keys/' + encodeURIComponent(k.id), 'DELETE')
       refresh()
-      notify('Key 已撤销，历史记录已保留。')
+      notify('Key 已撤销，历史记录已保留；如需彻底移除可点击“删除”。')
+    })
+  }
+
+  function purge(k: Key) {
+    if (!confirm(`确定永久删除 Key“${k.name}”？删除后不可恢复，历史调用记录会保留。`)) return
+    action(async () => {
+      await api('/keys/' + encodeURIComponent(k.id) + '/purge', 'DELETE')
+      refresh()
+      notify('Key 已删除，历史记录已保留。')
     })
   }
 
@@ -108,7 +117,9 @@ export function KeysPage({ keys, stats, channels, timezone, busy, error, notice,
             <>{time(k.expires_at) === '—' ? '永不过期' : time(k.expires_at)}<small className="sub">创建于 {time(k.created_at)}</small></>,
             <div className="actions">
               <button disabled={busy || k.revoked} onClick={() => toggle(k)}>{k.enabled ? '停用' : '启用'}</button>
-              <button className="danger" disabled={busy} onClick={() => revoke(k)}>撤销</button>
+              {k.revoked
+                ? <button className="danger" disabled={busy} onClick={() => purge(k)}>删除</button>
+                : <button className="danger" disabled={busy} onClick={() => revoke(k)}>撤销</button>}
             </div>,
           ]
         })}