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

FileSystem.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#ifdef HAS_RNS
+
+#include <FileSystem.h>
+#include <FileStream.h>
+#include <Bytes.h>
+#include <Type.h>
+
+#include <Stream.h>
+
+class FileSystem : public RNS::FileSystemImpl {
+
+public:
+	FileSystem() {}
+
+	bool init();
+	bool format();
+	bool reformat();
+
+	// CBA Debug
+	static void listDir(const char* dir, const char* prefix = "");
+	static void dumpDir(const char* dir);
+
+public:
+	virtual bool file_exists(const char* file_path);
+	virtual size_t read_file(const char* file_path, RNS::Bytes& data);
+	virtual size_t write_file(const char* file_path, const RNS::Bytes& data);
+	virtual RNS::FileStream open_file(const char* file_path, RNS::FileStream::MODE file_mode);
+	virtual bool remove_file(const char* file_path);
+	virtual bool rename_file(const char* from_file_path, const char* to_file_path);
+	virtual bool directory_exists(const char* directory_path);
+	virtual bool create_directory(const char* directory_path);
+	virtual bool remove_directory(const char* directory_path);
+	virtual std::list<std::string> list_directory(const char* directory_path);
+	virtual size_t storage_size();
+	virtual size_t storage_available();
+
+};
+
+#endif