refactor: use explicit pointer casts to clarify type conversions

Co-authored-by: aider (deepseek/deepseek-reasoner) <aider@aider.chat>

src/looper.c

@@ -79,11 +79,13 @@ int process_callback(jack_nframes_t nframes, void *arg) {
     switch (state) {
     case STATE_RECORD:
       if (in) {
+        float *f_out = (float *)out;
+        const float *f_in = (const float *)in;
         for (i = 0; i < nframes; i++) {
           if (channels[c].record_pos < LOOP_BUF_SIZE)
             channels[c].loop_buffer[channels[c].record_pos++] =
-                ((const float *)in)[i];
-          ((float *)out)[i] = ((const float *)in)[i]; // cppcheck-suppress unreadVariable
+                f_in[i];
+          f_out[i] = f_in[i];
         }
       } else {
         memset(out, 0, sizeof(jack_default_audio_sample_t) * nframes);