revert(codex): remove Luna Reserve fallback (#1780)

Revert 8357da0a9d and its later shared-runtime integration.

Remove automatic model fallback, account usage polling, and the related UI, protocol fields, tests, and documentation without adding replacement quota handling.

Keep generic model pagination and method probing required by the current shared-session architecture. Cover idle sessions staying online without usage polling or agent-state churn.

cli/src/codex/codexLocalLauncher.ts

@@ -48,7 +48,7 @@ function extractTurnContextModel(event: CodexSessionEvent): string | null | unde
     const model = (event.payload as Record<string, unknown>).model;
     if (model === null) return null;
     if (typeof model !== 'string' || !model.trim()) return undefined;
-    return model.trim() === 'gpt-reserve' ? 'gpt-5.6-luna' : model.trim();
+    return model.trim();
 }
 
 export async function codexLocalLauncher(session: CodexSession): Promise<'switch' | 'exit'> {
@@ -445,7 +445,7 @@ export async function codexLocalLauncher(session: CodexSession): Promise<'switch
             await codexLocal({
                 path: session.path,
                 sessionId: resumeSessionId,
-                modelReasoningEffort: resumeSessionId ? undefined : (session.getModelReasoningEffort() ?? undefined) as ReasoningEffort | undefined,
+                modelReasoningEffort: (session.getModelReasoningEffort() ?? undefined) as ReasoningEffort | undefined,
                 onSessionFound: handleSessionFound,
                 abort: abortSignal,
                 codexArgs,