Fix browser closure timing in search agent

Move defer statement to ensure browser closure occurs only after assigning the browser to the context. This prevents potential issues of premature resource release.

pkg/agents/knowledge_processor.go

@@ -55,7 +55,6 @@ Here is the knowledge I have gathered from ` + fmt.Sprint(len(sources)) + ` sour
 
 	res, err := a.WithSystemPrompt(systemPrompt).
 		WithSystemPromptSuffix(``).
-		WithToolbox(nil).
 		CallAndExecute(ctx)
 	if err != nil {
 		return "", err
@@ -102,7 +101,6 @@ The moon is 4.5 billion years old [1,2], 238,855 miles away from the Earth [3],
 
 	res, err = a.WithSystemPrompt(systemPrompt).
 		WithSystemPromptSuffix(``).
-		WithToolbox(nil).
 		CallAndExecute(ctx, gollm.Message{Role: gollm.RoleSystem, Text: providedIntel}, summarizedData)
 
 	if err != nil {