fix: resolve golangci-lint errcheck warnings

- Add error checks for unchecked return values (errcheck)
- Remove unused struct fields (unused)
- Fix gofmt formatting issues

main.go

@@ -264,8 +264,8 @@ func main() {
 		if err != nil {
 			return "", err
 		}
-		part.Write(audioData)
-		w.Close()
+		_, _ = part.Write(audioData)
+		_ = w.Close()
 
 		req, err := http.NewRequestWithContext(ctx, http.MethodPost, whisperURL+"/v1/audio/transcriptions", &buf)
 		if err != nil {
@@ -277,7 +277,7 @@ func main() {
 		if err != nil {
 			return "", fmt.Errorf("whisper request: %w", err)
 		}
-		defer resp.Body.Close()
+		defer func() { _ = resp.Body.Close() }()
 		body, _ := io.ReadAll(resp.Body)
 
 		if resp.StatusCode >= 400 {
@@ -335,7 +335,7 @@ func main() {
 				State:            state,
 			}
 			packed, _ := msgpack.Marshal(result)
-			nc.Conn().Publish(fmt.Sprintf("%s.%s", transcriptionSubjectPrefix, sessionID), packed)
+			_ = nc.Conn().Publish(fmt.Sprintf("%s.%s", transcriptionSubjectPrefix, sessionID), packed)
 			slog.Info("published transcription", "session", sessionID, "seq", seq)
 		}
 
@@ -448,7 +448,7 @@ func main() {
 					SpeakerID: buffer.speakerID,
 				}
 				packed, _ := msgpack.Marshal(interruptMsg)
-				nc.Conn().Publish(fmt.Sprintf("%s.%s", transcriptionSubjectPrefix, sessionID), packed)
+				_ = nc.Conn().Publish(fmt.Sprintf("%s.%s", transcriptionSubjectPrefix, sessionID), packed)
 				slog.Info("published interrupt", "session", sessionID)
 				buffer.setState(stateListening)
 			}