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

FileStream.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#ifdef HAS_RNS
+
+#include "FileSystem.h"
+#include "FileSystemType.h"
+
+	class FileStream : public RNS::FileStreamImpl {
+
+	private:
+		std::unique_ptr<File> _file;
+		bool _closed = false;
+
+	public:
+		FileStream(File* file) : RNS::FileStreamImpl(), _file(file) {}
+		virtual ~FileStream() { if (!_closed) close(); }
+
+	public:
+		inline virtual const char* name() { return _file->name(); }
+		inline virtual size_t size() { return _file->size(); }
+		inline virtual void close() { _closed = true; _file->close(); }
+
+		// Print overrides
+		inline virtual size_t write(uint8_t byte) { return _file->write(byte); }
+		inline virtual size_t write(const uint8_t *buffer, size_t size) { return _file->write(buffer, size); }
+
+		// Stream overrides
+		inline virtual int available() { return _file->available(); }
+		inline virtual int read() { return _file->read(); }
+		inline virtual int peek() { return _file->peek(); }
+		inline virtual void flush() { _file->flush(); }
+
+	};
+
+#endif