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/additional_rate_limit_details.rs

@@ -0,0 +1,38 @@
+/*
+ * codex-backend
+ *
+ * codex-backend
+ *
+ * The version of the OpenAPI document: 0.0.1
+ *
+ * Generated by: https://openapi-generator.tech
+ */
+
+use crate::models;
+use serde::Deserialize;
+use serde::Serialize;
+
+#[derive(Clone, Default, Debug, PartialEq, Serialize, Deserialize)]
+pub struct AdditionalRateLimitDetails {
+    #[serde(rename = "limit_name")]
+    pub limit_name: String,
+    #[serde(rename = "metered_feature")]
+    pub metered_feature: String,
+    #[serde(
+        rename = "rate_limit",
+        default,
+        with = "::serde_with::rust::double_option",
+        skip_serializing_if = "Option::is_none"
+    )]
+    pub rate_limit: Option<Option<Box<models::RateLimitStatusDetails>>>,
+}
+
+impl AdditionalRateLimitDetails {
+    pub fn new(limit_name: String, metered_feature: String) -> AdditionalRateLimitDetails {
+        AdditionalRateLimitDetails {
+            limit_name,
+            metered_feature,
+            rate_limit: None,
+        }
+    }
+}