feat(userspace): add ring-3 runtime startup and syscall wrappers

user/ulib.h

@@ -0,0 +1,27 @@
+#ifndef FROSTBYTE_ULIB_H
+#define FROSTBYTE_ULIB_H
+
+#include "syscall.h"
+#include "fs.h"
+
+long userWrite(int fd, const char* buffer, unsigned long length);
+long userRead(int fd, char* buffer, unsigned long length);
+void userExit(int code);
+long userYield(void);
+long userGetpid(void);
+void* userSbrk(long increment);
+void userSleep(unsigned long milliseconds);
+
+long userOpen(const char* path, unsigned int flags);
+long userClose(int fd);
+long userLseek(int fd, long offset, int whence);
+long userStat(const char* path, FbStat* out);
+long userGetdents(int fd, FbDirent* out, unsigned long length);
+long userMkdir(const char* path);
+long userUnlink(const char* path);
+
+void print(const char* text);
+void printDec(long value);
+unsigned long stringLength(const char* text);
+
+#endif