feat: push loop output into save ring during playback

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

src/looper.c

@@ -127,6 +127,14 @@ int process_callback(jack_nframes_t nframes, void *arg) {
       break;
     }
 
+    /* push loop output into save ring if saving */
+    if (channels[c].save_ring != NULL) {
+      if (state == STATE_LOOPING && channels[c].loop_count > 0) {
+          float *outf = (float *)out;
+          ring_write(channels[c].save_ring, outf, nframes);
+      }
+    }
+
     channels[c].prev_state = state;
   }