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-validator/pd.rego

@@ -100,7 +100,7 @@ violation contains msg if {
     msg := sprintf("connect[%d]/[%d]: duplicate (%d,%d)->(%d,%d)", [a.x_index, b.x_index, a.src, a.outlet, a.dst, a.inlet])
 }
 
-# Signal-to-control connection
+# Signal-to-control connection (skip unknown objects — might be abstractions with inlet~)
 violation contains msg if {
     some rec in input.records
     rec.type == "connect"
@@ -110,6 +110,7 @@ violation contains msg if {
     dst_rec.type == "obj"
     is_signal(src_rec.name)
     not is_signal(dst_rec.name)
+    known_inlets[dst_rec.name]
     msg := sprintf("connect[%d]: signal (~) outlet %d (%s) to control inlet %d (%s)", [rec.x_index, rec.src, src_rec.name, rec.dst, dst_rec.name])
 }
 
@@ -137,11 +138,14 @@ violation contains msg if {
 }
 
 # Inlet exceeds known count (skip -1 = variable)
+# Skip outlet objects (valid in abstractions) and unknown abstractions
 violation contains msg if {
     some rec in input.records
     rec.type == "connect"
     dst_rec := record_by_idx(rec.dst)
     dst_rec.type == "obj"
+    dst_rec.name != "outlet"
+    dst_rec.name != "outlet~"
     known_inlets[dst_rec.name]
     known_inlets[dst_rec.name] != -1
     rec.inlet >= known_inlets[dst_rec.name]