refactor: add helpers for file I/O, main script detection, and safe strncpy, make hal generic

src/pxl8_macros.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <string.h>
+
 #ifndef pxl8_min
 #define pxl8_min(a, b) ((a) < (b) ? (a) : (b))
 #endif
@@ -7,3 +9,10 @@
 #ifndef pxl8_max
 #define pxl8_max(a, b) ((a) > (b) ? (a) : (b))
 #endif
+
+#ifndef pxl8_strncpy
+#define pxl8_strncpy(dst, src, size) do { \
+    strncpy((dst), (src), (size) - 1); \
+    (dst)[(size) - 1] = '\0'; \
+} while (0)
+#endif