feat: add openai model info configuration (#551)

In reference to [Issue 548](https://github.com/openai/codex/issues/548)
- part 1.

codex-cli/tests/model-info.test.ts

@@ -0,0 +1,19 @@
+import { describe, expect, test } from "vitest";
+import { openAiModelInfo } from "../src/utils/model-info";
+
+describe("Model Info", () => {
+  test("supportedModelInfo contains expected models", () => {
+    expect(openAiModelInfo).toHaveProperty("gpt-4o");
+    expect(openAiModelInfo).toHaveProperty("gpt-4.1");
+    expect(openAiModelInfo).toHaveProperty("o3");
+  });
+
+  test("model info entries have required properties", () => {
+    Object.entries(openAiModelInfo).forEach(([_, info]) => {
+      expect(info).toHaveProperty("label");
+      expect(info).toHaveProperty("maxContextLength");
+      expect(typeof info.label).toBe("string");
+      expect(typeof info.maxContextLength).toBe("number");
+    });
+  });
+});