feat(pool): one board of pools with split/merge by drag; plan names from tier and seat

- The Users page account pool is one board: a column per pool holding its
  Claude Code, Codex and Cursor accounts (plan, quota, live panes) and its
  members. Accounts sit in one pool; drag moves them. Drop on New pool to
  split one off; drag a pool's only account into another pool to merge
  (members follow, the emptied pool is deleted on Save). One password Save.
- Claude plan label (planLabel in cc-profiles.js) reads rateLimitTier and
  seatTier: Max 5x/20x, Team Standard/Premium — subscriptionType alone said
  'pro' after an upgrade and 'team' for both seats. Shown on profiles, the
  status bar quota badge and pool cards; Codex pool cards show the ChatGPT plan.

server/__tests__/quota.test.js

@@ -222,7 +222,7 @@ test("the live row is the account its token belongs to, not the one .claude.json
     assert.strictEqual(live.label, "Victor");
     assert.strictEqual(live.account, "victor@x.y");
     assert.strictEqual(live.ownerUuid, undefined);
-    assert.strictEqual(live.plan, "max");
+    assert.strictEqual(live.plan, "Max");
     assert.deepStrictEqual(
       claude.filter((t) => !t.active).map((t) => t.label),
       ["Thắng"]