fix: macOS bcopy conflict and Docker host binding

- Fix #11: Guard bcopy/bzero declarations with _VISUALCPP in commoninclude.h
  to avoid redefinition errors on macOS where <strings.h> provides them
- Fix #12: Add --host flag to serve command, default 127.0.0.1
  Docker now binds to 0.0.0.0 so Colima can reach the server from host
- Also fix truncate() panic when n < 3

third_party/akaiutil/commoninclude.h

@@ -185,8 +185,10 @@ extern int optopt;
 #define LSEEK64 lseek64
 #endif
 
+#ifdef _VISUALCPP
 extern void bcopy(const void *src,void *dst,size_t len);
 extern void bzero(void *b,size_t len);
+#endif