feat: QR Codes (#226)

* code gen updates

* qrcode support

* remove opacity on toast

* update item view to use tab-like pages

* adjust view for cards

* fix old API calls for ioutils

* move embed

* extract QR code

* add docs for QR codes

* add QR code

backend/app/api/handlers/v1/v1_ctrl_qrcode.go

@@ -0,0 +1,67 @@
+package v1
+
+import (
+	"bytes"
+	"image/png"
+	"io"
+	"net/http"
+
+	"github.com/hay-kot/homebox/backend/internal/sys/validate"
+	"github.com/hay-kot/homebox/backend/pkgs/server"
+	"github.com/yeqown/go-qrcode/v2"
+	"github.com/yeqown/go-qrcode/writer/standard"
+
+	_ "embed"
+)
+
+//go:embed assets/QRIcon.png
+var qrcodeLogo []byte
+
+// HandleGenerateQRCode godoc
+//
+//	@Summary  Encode data into QRCode
+//	@Tags     Items
+//	@Produce  json
+//	@Param    data      query    string   false "data to be encoded into qrcode"
+//	@Success 200 {string} string "image/jpeg"
+//	@Router   /v1/qrcode [GET]
+//	@Security Bearer
+func (ctrl *V1Controller) HandleGenerateQRCode() server.HandlerFunc {
+	const MaxLength = 4_296 // assume alphanumeric characters only
+
+	return func(w http.ResponseWriter, r *http.Request) error {
+		data := r.URL.Query().Get("data")
+
+		image, err := png.Decode(bytes.NewReader(qrcodeLogo))
+		if err != nil {
+			panic(err)
+		}
+
+		if len(data) > MaxLength {
+			return validate.NewFieldErrors(validate.FieldError{
+				Field: "data",
+				Error: "max length is 4,296 characters exceeded",
+			})
+		}
+
+		qrc, err := qrcode.New(data)
+		if err != nil {
+			return err
+		}
+
+		toWriteCloser := struct {
+			io.Writer
+			io.Closer
+		}{
+			Writer: w,
+			Closer: io.NopCloser(nil),
+		}
+
+		qrwriter := standard.NewWithWriter(toWriteCloser, standard.WithLogoImage(image))
+
+		// Return the QR code as a jpeg image
+		w.Header().Set("Content-Type", "image/jpeg")
+		w.Header().Set("Content-Disposition", "attachment; filename=qrcode.jpg")
+		return qrc.Save(qrwriter)
+	}
+}