Initial import: robot firmware + PlatformIO two-env scaffold

Robot-side firmware (Teensy 4.0) imported unchanged as extracted.
platformio.ini defines [env:robot] (teensy40) and [env:remote]
(teensy41); scripts/select_src_dir.py points each env at its own
sketch folder so robot/ and remote/ stay Arduino-style sketches.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-current/robot/Comms.cpp

@@ -0,0 +1,28 @@
+#include "Comms.h"
+#include "Config.h"
+#include <RF24.h>
+#include <SPI.h>
+
+static RF24 radio(RADIO_CE_PIN, RADIO_CSN_PIN);
+
+bool Comms::begin() {
+  radio_present_ = radio.begin();
+  if (radio_present_) {
+    radio.openReadingPipe(1, RADIO_ADDRESS);
+    radio.setPALevel(RF24_PA_LOW);
+    radio.setDataRate(RF24_250KBPS);
+    radio.setChannel(96);          // pick one clear of your local Wi-Fi
+    radio.startListening();
+  }
+  return radio_present_;
+}
+
+void Comms::update() {
+  if (radio_present_) {
+    while (radio.available()) {
+      radio.read(&packet_, sizeof(packet_));
+      last_rx_ms_ = millis();
+    }
+  }
+  link_ok_ = (millis() - last_rx_ms_) < (uint32_t)(LINK_TIMEOUT_SEC * 1000);
+}