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.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+	qrcode "github.com/skip2/go-qrcode"
+)
+
+func main() {
+	qr, err := qrcode.New("unsandbox-qr-ok", qrcode.Medium)
+	if err != nil {
+		panic(err)
+	}
+	rows := len(qr.Bitmap())
+	fmt.Printf("QR:unsandbox-qr-ok:ROWS:%d\n", rows)
+}