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/pty-run.js

@@ -488,6 +488,8 @@ function spawnRun(args) {
     entry.launcher === "codex" && !proxyProfile
       ? require("./codex-pool").forSpawn(require("./run-as").accountForLane(laneId), laneOwner)
       : null;
+  // Cursor's pool is API keys only (cursor-pool.js): CURSOR_API_KEY through `-e`.
+  const cursorPool = tool === "cursor" ? require("./cursor-pool").forSpawn(laneOwner) : null;
   const paneCred = require("./auth").newPaneToken();
   // A member's omp on the host's shared omp login (omp-share.js): its
   // models.yml points at the loopback gateway, with a key already listed there.
@@ -611,7 +613,7 @@ function spawnRun(args) {
       resumeSessionId: resumeSessionId || null,
       worktree: worktree === true || inWorktree === true,
       proxy: proxyProfile ? proxyProfile.name : null,
-      account: (poolAccount || codexPool)?.name ?? null,
+      account: (poolAccount || codexPool || cursorPool)?.name ?? null,
       paneTokenHash: paneCred ? paneCred.hash : null,
       prompt: initialPrompt || "",
       status: "running",
@@ -668,6 +670,7 @@ function spawnRun(args) {
     // this process only. Through tmux `-e`, never typed into the pane.
     ...(poolAccount ? poolAccount.env : {}),
     ...(codexPool ? codexPool.env : {}),
+    ...(cursorPool ? cursorPool.env : {}),
     ...(ompShare ? ompShare.env : {}),
     // Server mode: the CLI, MCP server and statusline in this pane act as the
     // workspace's owner with it (server/lib/auth.js userFromPaneToken).