Revert "fix: improve GitHub Copilot integration"

This reverts commit 21a9b3b66f.

src/commands/auth-choice.apply.github-copilot.ts

@@ -35,7 +35,7 @@ export async function applyAuthChoiceGitHubCopilot(
   nextConfig = applyAuthProfileConfig(nextConfig, {
     profileId: "github-copilot:github",
     provider: "github-copilot",
-    mode: "oauth",
+    mode: "token",
   });
 
   if (params.setDefaultModel) {