Codex accounts: 6h auto-refresh, manual refresh, manual switch (#48)

Auto refresh
- New refreshCodexAccount(index) calls https://auth.openai.com/oauth/token
  with grant_type=refresh_token and persists rotated tokens back to
  ~/.codex-accounts/{N}/auth.json. JWT's subscription_active_until
  reflects the latest plan state OpenAI hands back.
- startCodexAccountRefreshLoop() runs every 6h (first run delayed 60s
  after boot to keep startup snappy). Hooked into main()/shutdown()
  alongside the existing claude token refresh loop.

Manual controls (Settings → 계정 → Codex)
- "갱신" button per row: forces an immediate refresh for that account.
- "전체 갱신" button: refreshes all codex accounts in sequence.
- "전환" button: writes data/codex-rotation-state.json so the next codex
  spawn picks the chosen account. Active account marked with a green-
  bordered card and "사용중" badge.

Endpoints
- POST /api/settings/accounts/codex/{i}/refresh
- POST /api/settings/accounts/codex/refresh-all
- PUT  /api/settings/accounts/codex/current  { index }
- GET  /api/settings/accounts now also returns codexCurrentIndex.

Why
JWTs cache subscription state at issue-time. When a Pro plan lapses or
a user upgrades/downgrades, the dashboard kept showing stale data until
the user logged in again. Periodic refresh + explicit "갱신" button
keeps the displayed state honest, and the manual switch unblocks the
user when rotation lands on a known-bad account.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

src/index.ts

@@ -59,6 +59,10 @@ import { startWebDashboardServer } from './web-dashboard-server.js';
 import { Channel, NewMessage, RegisteredGroup } from './types.js';
 import { logger } from './logger.js';
 import { initCodexTokenRotation } from './codex-token-rotation.js';
+import {
+  startCodexAccountRefreshLoop,
+  stopCodexAccountRefreshLoop,
+} from './settings-store.js';
 import {
   hasAvailableClaudeToken,
   initTokenRotation,
@@ -245,6 +249,7 @@ async function main(): Promise<void> {
   initTokenRotation();
   initCodexTokenRotation();
   startTokenRefreshLoop();
+  startCodexAccountRefreshLoop();
 
   runtimeState.loadState();
 
@@ -254,6 +259,7 @@ async function main(): Promise<void> {
   const shutdown = async (signal: string) => {
     logger.info({ signal }, 'Shutdown signal received');
     stopTokenRefreshLoop();
+    stopCodexAccountRefreshLoop();
     if (leaseRecoveryTimer) {
       clearInterval(leaseRecoveryTimer);
       leaseRecoveryTimer = null;