feat(kanban): partition local queues by account

req: sync/020

req: auth/005

req: security/004

req: operations/002

examples/kanban/templates/sync_shell.heml

@@ -10,6 +10,7 @@
     <h2 id="sync-title">Sync status</h2>
     <p role="status" aria-live="polite">Waiting for pending commands.</p>
     <button type="button" data-sync-retry>Retry sync now</button>
+    <button type="button" data-sync-export disabled>Export this account's queue</button>
   </section>
   <script +src="self.runtime_src" defer></script>
   <script src="/sync.js" defer></script>