feat: account pool per tool with groups and a Cursor pool; update runs in the background

- The update dialog can be closed while an update applies: it keeps running,
  the page still reloads itself when the new server is up, and a failure
  re-opens the dialog with its error.
- Account pool card: one tab per AI tool (Claude Code, Codex, Cursor CLI,
  Oh My Pi, and every other installed tool, which says it has no pool),
  accounts as cards with 5-hour and weekly quota shown as what is LEFT plus
  their reset times, and the saved profiles of Settings → AI tools →
  Profiles as cards with "Share to pool".
- Cursor account pool (server/lib/cursor-pool.js): Cursor API keys handed to
  a cursor-agent pane only through tmux -e CURSOR_API_KEY;
  `agenthub accounts add <name> --tool cursor`.
- Pool groups (server/lib/pool-groups.js, /api/accounts/groups): a group's
  members run only on its accounts of each tool, a user in no group on the
  accounts no group lists, a pin still wins. account_pins loses its tool
  CHECK (rebuilt, pins kept); three new tables.
- Oh My Pi login sharing can be switched from its pool tab too.

server/lib/codex-pool.js

@@ -358,6 +358,10 @@ function pick(member, ownerId = null) {
       live = usable.find((a) => a.kind === "chatgpt" && liveInHome(a.name, member)) || null;
     }
   }
+  // The owner's group's accounts only (pool-groups.js) — a login already live
+  // in their home stays: one auth.json per home.
+  const allowed = require("./pool-groups").allowed(ownerId, "codex");
+  usable = usable.filter((a) => allowed(a.name));
   // A pinned API key goes in by env and wins outright; a pinned ChatGPT login
   // waits while another login holds this home.
   const pin = require("./account-pins").pinFor(ownerId, "codex");