feat: support multiple rate limits (#11260)

Added multi-limit support end-to-end by carrying limit_name in
rate-limit snapshots and handling multiple buckets instead of only
codex.
Extended /usage client parsing to consume additional_rate_limits
Updated TUI /status and in-memory state to store/render per-limit
snapshots
Extended app-server rate-limit read response: kept rate_limits and added
rate_limits_by_name.
Adjusted usage-limit error messaging for non-default codex limit buckets

codex-rs/codex-backend-openapi-models/src/models/rate_limit_status_payload.rs

@@ -30,6 +30,13 @@ pub struct RateLimitStatusPayload {
         skip_serializing_if = "Option::is_none"
     )]
     pub credits: Option<Option<Box<models::CreditStatusDetails>>>,
+    #[serde(
+        rename = "additional_rate_limits",
+        default,
+        with = "::serde_with::rust::double_option",
+        skip_serializing_if = "Option::is_none"
+    )]
+    pub additional_rate_limits: Option<Option<Vec<models::AdditionalRateLimitDetails>>>,
 }
 
 impl RateLimitStatusPayload {
@@ -38,6 +45,7 @@ impl RateLimitStatusPayload {
             plan_type,
             rate_limit: None,
             credits: None,
+            additional_rate_limits: None,
         }
     }
 }