refactor: 3-module pd architecture + viz non-blocking fix

- midi-in.pd: netreceive -> route -> unpack -> pitch/velocity outlets
- audio-out.pd: inlet~ -> dac~ abstraction
- synth.pd: consumer patch wiring midi-in -> voice -> audio-out
- led-matrix-viz.py: router socket non-blocking, registered with poller
- pd.rego: skip outlet/abstraction false positives in validation

pd/midi-in.pd

@@ -0,0 +1,14 @@
+#N canvas 0 0 300 200 10;
+#X obj 40 20 netreceive -u 8081;
+#X obj 40 50 route midi;
+#X obj 40 80 route 144 128;
+#X obj 40 110 unpack 0 0;
+#X obj 40 150 outlet;
+#X obj 120 150 outlet;
+#X text 155 150 pitch;
+#X text 155 170 velocity;
+#X connect 0 0 1 0;
+#X connect 1 0 2 0;
+#X connect 2 0 3 0;
+#X connect 3 0 4 0;
+#X connect 3 1 5 0;