fix(qr): rewrite 7 failing language tests to use native C FFI

All use dlopen/dlsym to libqrencode.so (system-wide via gcc role):
- Haskell: System.Posix.DynamicLinker + foreign import ccall "dynamic"
- F#: Mono P/Invoke DllImport("libqrencode.so")
- COBOL: LINKAGE SECTION for proper struct pointer access
- Nim: dynlib module (loadLib/symAddr)
- Fortran: renamed dlclose binding to avoid symbol collision
- D: core.sys.posix.dlfcn (dlopen/dlsym)
- OCaml: Ctypes.foreign via ocamlfind #require

test/qr.d

@@ -1,8 +1,33 @@
+import core.sys.posix.dlfcn;
 import std.stdio;
-import qr;
+import std.string;
+
+struct QRcode {
+    int _version;
+    int width;
+    void* data;
+}
 
 void main() {
-    auto qrCode = QrCode("unsandbox-qr-ok");
-    auto size = qrCode.size;
-    writefln("QR:unsandbox-qr-ok:ROWS:%d", size);
+    auto lib = dlopen("libqrencode.so", RTLD_LAZY);
+    if (lib is null) {
+        stderr.writeln("dlopen: ", dlerror().fromStringz);
+        return;
+    }
+
+    alias EncFunc = extern(C) QRcode* function(const char*, int, int, int, int);
+    alias FreeFunc = extern(C) void function(QRcode*);
+
+    auto encode = cast(EncFunc) dlsym(lib, "QRcode_encodeString");
+    auto qfree = cast(FreeFunc) dlsym(lib, "QRcode_free");
+
+    auto qr = encode("unsandbox-qr-ok", 0, 1, 2, 1);
+    if (qr is null) {
+        stderr.writeln("encode failed");
+        return;
+    }
+
+    writefln("QR:unsandbox-qr-ok:ROWS:%d", qr.width);
+    qfree(qr);
+    dlclose(lib);
 }