Initial commit: RNodeTHV4 boundary mode firmware for Heltec V4

Bridges LoRa mesh and TCP/WiFi backbone networks using microReticulum.
Based on microReticulum_Firmware with boundary mode additions:
- BoundaryMode.h: State management and EEPROM persistence
- BoundaryConfig.h: WiFi captive portal for configuration
- TcpInterface.h: TCP backbone interface with HDLC framing
- Display.h: Custom OLED layout with network status indicators
- Transport/Identity library patches for embedded memory constraints

variants/rak11200/pins_arduino.h

@@ -0,0 +1,64 @@
+#ifndef Pins_Arduino_h
+#define Pins_Arduino_h
+
+#ifndef _VARIANT_RAK11200_
+#define _VARIANT_RAK11200_
+#endif
+
+#include <stdint.h>
+
+// #ifndef EXTERNAL_NUM_INTERRUPTS
+// #define EXTERNAL_NUM_INTERRUPTS 16
+// #endif
+// #ifndef NUM_DIGITAL_PINS
+// #define NUM_DIGITAL_PINS 40
+// #endif
+// #ifndef NUM_ANALOG_INPUTS
+// #define NUM_ANALOG_INPUTS 16
+// #endif
+// #ifndef analogInputToDigitalPin
+// #define analogInputToDigitalPin(p) (((p) < 20) ? (esp32_adc2gpio[(p)]) : -1)
+// #endif
+// #ifndef digitalPinToInterrupt
+// #define digitalPinToInterrupt(p) (((p) < 40) ? (p) : -1)
+// #endif
+// #ifndef digitalPinHasPWM
+// #define digitalPinHasPWM(p) (p < 34)
+// #endif
+
+#define LED_GREEN              12
+#define LED_BLUE             2
+
+#ifdef LED_BUILTIN
+#undef LED_BUILTIN
+#endif
+#define LED_BUILTIN          LED_GREEN
+
+static const uint8_t TX = 1;
+static const uint8_t RX = 3;
+
+#define TX1 21
+#define RX1 19
+
+#define WB_IO1 14
+#define WB_IO2 27
+#define WB_IO3 26
+#define WB_IO4 23
+#define WB_IO5 13
+#define WB_IO6 22
+#define WB_SW1 34
+#define WB_A0 36
+#define WB_A1 39
+#define WB_CS 32
+#define WB_LED1 12
+#define WB_LED2 2
+
+static const uint8_t SDA = 4;
+static const uint8_t SCL = 5;
+
+static const uint8_t SS = 32;
+static const uint8_t MOSI = 25;
+static const uint8_t MISO = 35;
+static const uint8_t SCK = 33;
+
+#endif /* Pins_Arduino_h */