feat(canary): shared 43-byte transparent GIF for image triggers

Used by webbug, docx, pdf, envfile triggers. Single source of truth.
Test asserts length, magic bytes, GIF89a trailer, and decodes via image/gif.

PROJECTS/beginner/canary-token-generator/backend/internal/token/generators/pixel/pixel.go

@@ -0,0 +1,13 @@
+// ©AngelaMos | 2026
+// pixel.go
+
+package pixel
+
+var TransparentGIF = []byte{
+	0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x01, 0x00, 0x01, 0x00, 0x80, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0x21, 0xf9, 0x04, 0x01, 0x00,
+	0x00, 0x00, 0x00, 0x2c, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00,
+	0x00, 0x02, 0x02, 0x44, 0x01, 0x00, 0x3b,
+}
+
+const ContentType = "image/gif"

PROJECTS/beginner/canary-token-generator/backend/internal/token/generators/pixel/pixel_test.go

@@ -0,0 +1,52 @@
+// ©AngelaMos | 2026
+// pixel_test.go
+
+package pixel_test
+
+import (
+	"bytes"
+	"image/gif"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/CarterPerez-dev/cybersecurity-projects/canary-token-generator/backend/internal/token/generators/pixel"
+)
+
+const (
+	expectedLength = 43
+	expectedWidth  = 1
+	expectedHeight = 1
+)
+
+var (
+	gif89aMagic = []byte{0x47, 0x49, 0x46, 0x38, 0x39, 0x61}
+	gifTrailer  = byte(0x3b)
+)
+
+func TestTransparentGIF_Length(t *testing.T) {
+	require.Len(t, pixel.TransparentGIF, expectedLength)
+}
+
+func TestTransparentGIF_MagicBytes(t *testing.T) {
+	require.True(t,
+		bytes.HasPrefix(pixel.TransparentGIF, gif89aMagic),
+		"expected GIF89a magic prefix, got % x", pixel.TransparentGIF[:len(gif89aMagic)],
+	)
+	require.Equal(t, gifTrailer, pixel.TransparentGIF[len(pixel.TransparentGIF)-1],
+		"expected trailing GIF terminator 0x3B")
+}
+
+func TestTransparentGIF_DecodesAsImageGIF(t *testing.T) {
+	img, err := gif.Decode(bytes.NewReader(pixel.TransparentGIF))
+	require.NoError(t, err)
+	require.NotNil(t, img)
+
+	bounds := img.Bounds()
+	require.Equal(t, expectedWidth, bounds.Dx())
+	require.Equal(t, expectedHeight, bounds.Dy())
+}
+
+func TestContentType_IsImageGIF(t *testing.T) {
+	require.Equal(t, "image/gif", pixel.ContentType)
+}