refactor: remove required constraints and empty API key fields

- Remove 'required' attribute from Codex auth.json textarea
- Remove conditional 'required' logic from API key input field
- Clean up Codex Official preset by removing null OPENAI_API_KEY entry
- Allow more flexible form validation while maintaining backend checks

src/config/codexProviderPresets.ts

@@ -62,9 +62,7 @@ export const codexProviderPresets: CodexProviderPreset[] = [
     websiteUrl: "https://chatgpt.com/codex",
     isOfficial: true,
     category: "official",
-    auth: {
-      OPENAI_API_KEY: null,
-    },
+    auth: {},
     config: ``,
     theme: {
       icon: "codex",