feat: add QR code functional tests across 41 languages

Native QR generation for each language's ecosystem:
- 27 languages use package manager QR libraries (qrcode, rqrcode, ZXing, etc.)
- 10 languages use C FFI to libqrencode (dlopen, ISO_C_BINDING, @cImport, critcl)
- 2 shell languages use qrencode CLI (native shell paradigm)
- 1 language (Prolog) uses C FFI with CLI fallback

Section 9 added to test-sdk.sh with get_qr_file() mapping and
QR:unsandbox-qr-ok:ROWS pattern validation across the hydra matrix.

test/qr.forth

@@ -0,0 +1,24 @@
+\c #include <dlfcn.h>
+\c #include <stdio.h>
+\c typedef struct { int version; int width; unsigned char *data; } QRcode;
+\c static void *qrlib;
+\c static QRcode* (*qr_enc)(const char*,int,int,int,int);
+\c static void (*qr_fr)(QRcode*);
+\c void qr_init(void) {
+\c   qrlib = dlopen("libqrencode.so", 2);
+\c   qr_enc = dlsym(qrlib, "QRcode_encodeString");
+\c   qr_fr = dlsym(qrlib, "QRcode_free");
+\c }
+\c int qr_width(void) {
+\c   QRcode *qr = qr_enc("unsandbox-qr-ok", 0, 1, 2, 1);
+\c   int w = qr->width;
+\c   qr_fr(qr);
+\c   return w;
+\c }
+
+c-function qr-init qr_init -- void
+c-function qr-width qr_width -- n
+
+qr-init
+." QR:unsandbox-qr-ok:ROWS:" qr-width 0 .r cr
+bye