Settings: show codex account email + subscription expiry (#45)

- Extract email and chatgpt_subscription_last_checked from codex JWT in
  addition to plan_type and subscription_active_until.
- Settings → 계정 row now displays: email · plan badge · expiry badge
  with active/soon/expired color coding (green/amber/red).
- Fix codex/.codex-accounts directory scan picking up sibling dirs like
  "1.bak-..." and double-counting an index (require dirname to be
  fully numeric).

Motivation: rotation was landing on accounts whose Pro/Team subscription
had silently expired, causing OpenAI to reject upper-tier models with
a misleading "model not supported" error. Surface expiry in the UI so
the user can see at a glance which accounts need renewal.

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

apps/dashboard/src/api.ts

@@ -355,8 +355,10 @@ export interface ClaudeAccountSummary {
 export interface CodexAccountSummary {
   index: number;
   accountId: string | null;
+  email: string | null;
   planType: string | null;
   subscriptionUntil: string | null;
+  subscriptionLastChecked: string | null;
   exists: boolean;
 }