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

boards/rak3112.json

@@ -0,0 +1,51 @@
+{
+	"build": {
+		"arduino": {
+			"ldscript": "esp32s3_out.ld",
+			"memory_type": "qio_opi"
+		},
+		"core": "esp32",
+		"extra_flags": [
+			"-DRAK3112",
+			"-DARDUINO_USB_CDC_ON_BOOT=1",
+			"-DARDUINO_USB_MODE=1",
+			"-DARDUINO_RUNNING_CORE=1",
+			"-DARDUINO_EVENT_RUNNING_CORE=1",
+			"-DBOARD_HAS_PSRAM"
+		],
+		"f_cpu": "240000000L",
+		"f_flash": "80000000L",
+		"flash_mode": "dio",
+		"hwids": [
+			[
+				"0x303A",
+				"0x1001"
+			]
+		],
+		"mcu": "esp32s3",
+		"variant": "rak3112"
+	},
+	"connectivity": [
+		"wifi",
+		"bluetooth"
+	],
+	"debug": {
+		"openocd_target": "esp32s3.cfg"
+	},
+	"frameworks": [
+		"arduino",
+		"espidf"
+	],
+	"name": "RAKwireless RAK3112",
+	"upload": {
+		"flash_size": "16MB",
+		"maximum_ram_size": 327680,
+		"maximum_size": 16777216,
+		"use_1200bps_touch": true,
+		"wait_for_upload_port": false,
+		"require_upload_port": true,
+		"speed": 921600
+	},
+	"url": "http://www.rakwireless.com/",
+	"vendor": "RAKwireless"
+}