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/protocol/src/protocol.rs

@@ -2000,6 +2000,21 @@ pub enum RateLimitReachedType {
     WorkspaceMemberUsageLimitReached,
 }
 
+impl FromStr for RateLimitReachedType {
+    type Err = String;
+
+    fn from_str(value: &str) -> Result<Self, Self::Err> {
+        match value {
+            "rate_limit_reached" => Ok(Self::RateLimitReached),
+            "workspace_owner_credits_depleted" => Ok(Self::WorkspaceOwnerCreditsDepleted),
+            "workspace_member_credits_depleted" => Ok(Self::WorkspaceMemberCreditsDepleted),
+            "workspace_owner_usage_limit_reached" => Ok(Self::WorkspaceOwnerUsageLimitReached),
+            "workspace_member_usage_limit_reached" => Ok(Self::WorkspaceMemberUsageLimitReached),
+            other => Err(format!("unknown rate limit reached type: {other}")),
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize, JsonSchema, TS)]
 pub struct RateLimitWindow {
     /// Percentage (0-100) of the window that has been consumed.