feat(server-s3): one Linux user per account (S3) — experimental

Server mode can now run each account as its own Linux user (ah-<name>)
when `agenthub server install-system` has set S3 up. The dashboard
reaches a member only through sudo -u / write-as / pane-launch, reads a
member's files only through owner- and type-checked opens, and hooks
are authenticated by peer uid. Local mode and server mode without S3
are unchanged.

EXPERIMENTAL: tested with fake sudo and fake accounts only. It has not
yet been verified on a real install with real member accounts, sudo or
a real Codex login. Do not offer it to real users yet.

- S3 core: provisioning, per-member tmux servers, the proxy key
  gateway, shared tools in /opt, dropped capabilities for children
  (P0–P5)
- P4: plan and quota per member home
- P6: ~/.claude.json seed; opt-in plugin baseline installed as the
  member; managed-settings spike script (not run)
- P7: Codex account pool (`agenthub accounts add --tool codex`)
- Roles merged with main's admin / analyst / developer: analysts write
  only their own rows, under S3 as well
- Per-account prefs: one implementation (Chat UI + onboarding)
- Security reviews F1–F49 (five rounds), each fix with a regression
  test: symlink/TOCTOU-safe member reads, no host writes in a member
  home, credentials and the data dir never served, owner and folder
  account must agree, pane tokens bound to the pane's uid, bounded
  sudo/tmux/git calls and member reads (no hang or crash from a member),
  async route rejections answer 500 instead of exiting
- Docs: docs/SERVER-MODE.md (S3 model, accepted ceilings, operator
  runbook), docs/plans/server-mode/S3-PLAN.md, CLAUDE.md S3 rules

Tests: server 2838/2841 (3 need 127.0.0.1:3000, held on this box);
client 1162/1162; tsc clean; headers check passes.

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

server/routes/accounts.js

@@ -2,21 +2,28 @@
  * @file accounts.js
  * @description `GET /api/accounts` — the Claude account pool as the balancer
  * sees it (server/lib/claude-pool.js): per account its live panes, $ spent in
- * the last 5 h / 7 d, the last quota reading and whether it counts as full.
- * Never a token. `?force=1` re-reads every quota first. Accounts are added and
+ * the last 5 h / 7 d, the last quota reading and whether it counts as full;
+ * `codex` is the same for the Codex pool (server/lib/codex-pool.js). Never a
+ * key or a token. `?force=1` re-reads every quota first. Accounts are added and
  * removed only from the host's shell (`agenthub accounts …`).
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 
 const { Router } = require("express");
 const pool = require("../lib/claude-pool");
+const codexPool = require("../lib/codex-pool");
 
 const router = Router();
 
 router.get("/", async (req, res) => {
   try {
     await pool.refreshQuotas({ force: req.query.force === "1" });
-    res.json({ accounts: pool.poolStatus(), blockPercent: pool.BLOCK_PERCENT });
+    if (req.query.force === "1") codexPool.resetQuota();
+    res.json({
+      accounts: pool.poolStatus(),
+      codex: codexPool.poolStatus(),
+      blockPercent: pool.BLOCK_PERCENT,
+    });
   } catch (e) {
     res.status(500).json({ error: { code: e.code || "EPOOL", message: e.message } });
   }