feat (auth): CLI OAuth supports pasting callback URLs to complete login

- Added callback URL resolution and terminal prompt logic
  - Codex/Claude/iFlow/Antigravity/Gemini login supports callback URL or local callback completion
  - Update Gemini login option signature and manager call
  - CLI default prompt function is compatible with null input to continue waiting

sdk/auth/gemini.go

@@ -44,7 +44,10 @@ func (a *GeminiAuthenticator) Login(ctx context.Context, cfg *config.Config, opt
 	}
 
 	geminiAuth := gemini.NewGeminiAuth()
-	_, err := geminiAuth.GetAuthenticatedClient(ctx, &ts, cfg, opts.NoBrowser)
+	_, err := geminiAuth.GetAuthenticatedClient(ctx, &ts, cfg, &gemini.WebLoginOptions{
+		NoBrowser: opts.NoBrowser,
+		Prompt:    opts.Prompt,
+	})
 	if err != nil {
 		return nil, fmt.Errorf("gemini authentication failed: %w", err)
 	}