Extend REAPER extension to read/write automation items, wire desktop app to it over UDP

extension-reaper-macos: split main.cpp into tracking.cpp (polls selected
envelope/automation items, reads/writes D_BASELINE) and socket.cpp (basic
UDP listener, non-blocking, drains all pending packets per tick). Nudging
now applies to every selected automation item across every track in the
project, not just the first one found.

app-desktop-macos: new "Extension" column (mirrors the OSC/Remote columns)
to enable/disable the UDP connection and point it at a host/port, plus a
log window. FocusFaderWidget gets an OSC/Ext output-mode toggle (mirrors
TransportWidget's MIDI/OSC toggle) so a fader can drive the extension
directly instead of/alongside OSC. Also renamed the Remote/Tablet buttons
for clarity and split their status indicator into its own column.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app-presets/presets.json

@@ -1,5 +1,5 @@
 {
-  "__last_used__": "preset5",
+  "__last_used__": "preset2",
   "presets": {
     "preset1": {
       "faders": [
@@ -938,7 +938,10 @@
     "osc_listen_port": 9001,
     "osc_send_port": 8000,
     "osc_running": true,
-    "tablet_running": true
+    "tablet_running": true,
+    "extension_ip": "127.0.0.1",
+    "extension_port": 9124,
+    "extension_running": true
   },
   "focus_toggles": [
     {
@@ -1257,7 +1260,7 @@
       "value": 73,
       "color": "Green",
       "pickup": false,
-      "last_sent": 62,
+      "last_sent": 73,
       "osc_addr_in": "/3/volume",
       "osc_addr_out": "/3/volume",
       "osc_addr_name": "/3/trackname",
@@ -1270,7 +1273,8 @@
       "hw_channel": 16,
       "hw_out_cc": 8,
       "hw_out_ch": 16,
-      "touch_sense_mode": "jl_cooper"
+      "touch_sense_mode": "jl_cooper",
+      "output_mode": "osc"
     },
     {
       "uid": "279a2c81-6548-422e-bf6d-75119c81b9c3",
@@ -1278,7 +1282,7 @@
       "value": 65,
       "color": "Gray",
       "pickup": false,
-      "last_sent": 42,
+      "last_sent": 65,
       "osc_addr_in": "/3/sendlevel1",
       "osc_addr_out": "/3/sendlevel1",
       "osc_addr_name": "/track/name",
@@ -1291,7 +1295,30 @@
       "hw_channel": 16,
       "hw_out_cc": 7,
       "hw_out_ch": 16,
-      "touch_sense_mode": "jl_cooper"
+      "touch_sense_mode": "jl_cooper",
+      "output_mode": "osc"
+    },
+    {
+      "uid": "8de2c4e9-2f05-4a71-a610-d712ee69d1a1",
+      "label": "Envelope Adjust",
+      "value": 45,
+      "color": "Gray",
+      "pickup": false,
+      "last_sent": 45,
+      "osc_addr_in": "/track/volume",
+      "osc_addr_out": "/track/volume",
+      "osc_addr_name": "/track/name",
+      "zone": null,
+      "center_index": null,
+      "zone_index": null,
+      "hardware_enabled": false,
+      "feedback_enabled": false,
+      "hw_cc": null,
+      "hw_channel": null,
+      "hw_out_cc": 7,
+      "hw_out_ch": 1,
+      "touch_sense_mode": "off",
+      "output_mode": "ext"
     }
   ]
 }