Compiles again, now with bootstrap-layer print implemented, but not yet tested.

To get print implemented, I also had to implement a lot of other things.

src/c/payloads/psse_string.c

@@ -0,0 +1,25 @@
+/**
+ *  payloads/string.c
+ *
+ *  A string cell.
+ *
+ *  (c) 2026 Simon Brooke <simon@journeyman.cc>
+ *  Licensed under GPL version 2.0, or, at your option, any later version.
+ */
+
+
+#include <stdint.h>
+
+ /*
+ * wide characters
+ */
+#include <wchar.h>
+#include <wctype.h>
+
+#include "memory/node.h"
+#include "memory/pointer.h"
+#include "memory/pso2.h"
+#include "memory/tags.h"
+
+#include "ops/string_ops.h"
+#include "ops/truth.h"