Bug bash 5: the URL, the fleet loop, and an empty card

A link to a hub page no longer reloads onto the last machine; a link from a hub-only page to
a machine's page arrives at that page; a page being left no longer asks about the next page's
selection; the hub holds its machines to the rate it is itself running.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

web/src/Docker.tsx

@@ -183,7 +183,7 @@ export default function Docker() {
   const [err, setErr] = useState('')
   const [tab, setTab] = useState<Tab>('containers')
   const [filter, setFilter] = useState('')
-  const [sel, setSel] = useHashSel()
+  const [sel, setSel] = useHashSel('docker')
   const [making, setMaking] = useState<'' | 'stack' | 'container'>('')
   const [dup, setDup] = useState<DupFrom | null>(null)
   const [startTask, setStartTask] = useState<{ name: string; id: string } | null>(null)