refactor: implement worker pool pattern, add persistent task queue, and decouple target loading logic

internal/analyzer/gemini.go

@@ -63,9 +63,9 @@ Respond STRICTLY with valid JSON matching the format:
 
 	resp, err := g.client.Do(req)
 	if err != nil {
-		return nil, fmt.Errorf("Gemini API call failed: %w", err)
+		return nil, fmt.Errorf("gemini api call failed: %w", err)
 	}
-	defer resp.Body.Close()
+	defer func() { _ = resp.Body.Close() }()
 
 	respBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
@@ -73,7 +73,7 @@ Respond STRICTLY with valid JSON matching the format:
 	}
 
 	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("Gemini API error (status %d): %s", resp.StatusCode, string(respBytes))
+		return nil, fmt.Errorf("gemini api error (status %d): %s", resp.StatusCode, string(respBytes))
 	}
 
 	var geminiResp struct {