Display workspace usage limit error copy from response header (#24114)

## Why

`openai/openai#947613` adds `X-Codex-Rate-Limit-Reached-Type` for Codex
workspace credit-depletion and spend-cap responses. The CLI currently
reads the adjacent promo header but otherwise renders generic
usage-limit copy, so those responses do not explain the
workspace-specific action the user needs to take.

Backend dependency: https://github.com/openai/openai/pull/947613

## What Changed

- Parse `X-Codex-Rate-Limit-Reached-Type` in the usage-limit error
handling path alongside `x-codex-promo-message`.
- Keep the header value parsing with the shared `RateLimitReachedType`
enum.
- Carry the parsed type on `UsageLimitReachedError` and render
client-owned copy for the four workspace owner/member credit and
spend-cap values.
- Preserve existing promo and plan-based text for absent, generic, or
unknown header values.
- Keep the existing TUI workspace-owner nudge state path unchanged; the
response header only selects the displayed error string.
- Add focused display coverage for all specific type values and the
generic fallback case.

## Test Plan

- Added `usage_limit_reached_error_formats_rate_limit_reached_types`
coverage.
- Not run manually, per request; CI runs validation on the pushed
commit.

codex-rs/codex-api/src/api_bridge_tests.rs

@@ -194,6 +194,37 @@ fn map_api_error_does_not_fallback_limit_name_to_limit_id() {
     );
 }
 
+#[test]
+fn map_api_error_ignores_unparseable_rate_limit_reached_type_headers() {
+    let values = [
+        http::HeaderValue::from_static("future_rate_limit_reached_type"),
+        http::HeaderValue::from_bytes(&[0xff]).expect("valid opaque header value"),
+    ];
+
+    for value in values {
+        let mut headers = HeaderMap::new();
+        headers.insert("x-codex-rate-limit-reached-type", value);
+        let body = serde_json::json!({
+            "error": {
+                "type": "usage_limit_reached",
+                "plan_type": "pro",
+            }
+        })
+        .to_string();
+        let err = map_api_error(ApiError::Transport(TransportError::Http {
+            status: http::StatusCode::TOO_MANY_REQUESTS,
+            url: Some("http://example.com/v1/responses".to_string()),
+            headers: Some(headers),
+            body: Some(body),
+        }));
+
+        let CodexErr::UsageLimitReached(usage_limit) = err else {
+            panic!("expected CodexErr::UsageLimitReached, got {err:?}");
+        };
+        assert_eq!(usage_limit.rate_limit_reached_type, None);
+    }
+}
+
 #[test]
 fn map_api_error_extracts_identity_auth_details_from_headers() {
     let mut headers = HeaderMap::new();