fix(codex): expose Fast for GPT-6 Sol and GPT-6 Luna (#5273)

The Codex Fast allowlist covered only gpt-6-astra in the GPT-6 family, so
selecting GPT-6 Sol or GPT-6 Luna published no fast_mode feature and the
composer had no Fast control to render. OpenAI documents Fast for Astra,
Sol, and Luna, and the app server's model/list advertises the fast speed
tier for all three.

Add both model IDs to the allowlist and to the parameterized feature test
covering the toggle, the restore path, and the serviceTier sent on turn
start.

The same change was proposed independently in #5220 and #5268.

Closes #5271

Co-authored-by: Ivan Malison <IvanMalison@gmail.com>
Co-authored-by: basilkhowaja <bk08432@st.habib.edu.pk>

packages/server/src/server/agent/providers/codex-app-server-agent.features.test.ts

@@ -99,6 +99,8 @@ async function createConnectedSession(
 describe("Codex app-server provider features", () => {
   test.each([
     "gpt-6-astra",
+    "gpt-6-sol",
+    "gpt-6-luna",
     "gpt-5.6",
     "gpt-5.6-sol",
     "gpt-5.6-terra",

packages/server/src/server/agent/providers/codex-feature-definitions.ts

@@ -4,6 +4,8 @@ import type { AgentFeature, AgentFeatureToggle } from "../agent-sdk-types.js";
 // https://developers.openai.com/codex/speed and https://developers.openai.com/codex/models.
 const CODEX_FAST_MODE_SUPPORTED_MODELS = new Set([
   "gpt-6-astra",
+  "gpt-6-sol",
+  "gpt-6-luna",
   "gpt-5.6",
   "gpt-5.6-sol",
   "gpt-5.6-terra",