Add Pro Max plan support and update Pro display names (#47971)

## What changed

- Recognize `promax` in authentication, account responses, and backend rate limits; update generated schemas and client types.
- Display `prolite` as “Pro”, `pro` as “Pro (More)”, and `promax` as “Pro (Max)” in account labels, status, and analytics.
- Include Pro Max in experimental context eligibility, paid-plan tooltips, and usage-limit guidance for purchasing credits.

## Testing

Extend coverage for Pro Max plan parsing, account and rate-limit responses, experimental context eligibility, and plan display names. Update the login token test to expect “Pro (More)”.

GitOrigin-RevId: 197e00fa7a99cbce125c8f1d43a451ec1ed5c1fb

codex-rs/core/src/session/token_budget.rs

@@ -14,7 +14,7 @@ fn experimental_context_is_eligible(auth_mode: AuthMode, plan_type: Option<PlanT
     auth_mode == AuthMode::Chatgpt
         && matches!(
             plan_type,
-            Some(PlanType::Plus | PlanType::Pro | PlanType::ProLite)
+            Some(PlanType::Plus | PlanType::Pro | PlanType::ProLite | PlanType::ProMax)
         )
 }
 
@@ -235,6 +235,7 @@ mod tests {
             (AuthMode::Chatgpt, PlanType::Plus, true),
             (AuthMode::Chatgpt, PlanType::Pro, true),
             (AuthMode::Chatgpt, PlanType::ProLite, true),
+            (AuthMode::Chatgpt, PlanType::ProMax, true),
             (AuthMode::Chatgpt, PlanType::Free, false),
             (AuthMode::Chatgpt, PlanType::Enterprise, false),
             (AuthMode::ApiKey, PlanType::Pro, false),