Initial tablet POC: project restructure + WebSocket/HTTP server + JS client

- Restructured project into /app, /server, /client with run.py entry point
- WSServer (QWebSocketServer) with log_signal, start/stop, client tracking
- HTTP server serves /client on port 8080
- Vanilla JS client: faders, toggles, transport, drag-to-arrange, lock/save layout
- Start Tablet button + floating Tablet log window in app UI
- Preset broadcast on load/switch, DAW state relay, hardware sync via widget_update
- Widget colors synced from app palette, toggle state fixed (sends 0/127 correctly)
- Layout saved per preset UUID back to presets.json

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/midi_ports.py

@@ -0,0 +1,33 @@
+import rtmidi
+
+def get_available_input_ports():
+    """Returns list of (display_name, original_index, available) for all ports."""
+    try:
+        all_ports = rtmidi.MidiIn().get_ports()
+    except:
+        return []
+
+    result = []
+
+    for i, name in enumerate(all_ports):
+        try:
+            test = rtmidi.MidiIn()
+            test.open_port(i)
+            test.close_port()
+            del test
+            result.append((name, i, True))
+        except:
+            print(f"Port in use, skipping: {name}")
+            result.append((f"{name}  [in use by another program]", i, False))
+
+    return result
+
+def open_midi_input_port(original_index, callback):
+    midi_in = rtmidi.MidiIn()
+    midi_in.open_port(original_index)
+    midi_in.set_callback(callback)
+    return midi_in
+
+def close_midi_input_port(midi_in):
+    if midi_in and midi_in.is_port_open():
+        midi_in.close_port()