One image request type instead of five (closes #307)

The new package internal/imagerequest holds the request type, its two
parts Source and Transform, the Format and Fit types, the dimension and
fit checks, the /v1/image/ path parsing and the variant key; it imports
no other package of pixa. imgcache.ParsedURL, imgcache.ImageRequest,
signature.Request, imageprocessor.Request, the second Size, format and
fit types and the conversions between them are gone. The image
processor takes a Transform only. encurl keeps a private struct with the
token's short CBOR field names. VariantKey moves with the function that
makes it. Tests follow the moved and renamed code; the tests of the
removed conversions go with them.

Model: opus-5-5

internal/imageprocessor/encoder_settings_internal_test.go

@@ -8,14 +8,17 @@ import (
 	"testing"
 
 	"github.com/davidbyttow/govips/v2/vips"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // processedSize runs input through Process and returns the output's size in
 // bytes.
-func processedSize(t *testing.T, input []byte, req *Request) int64 {
+func processedSize(
+	t *testing.T, input []byte, transform *imagerequest.Transform,
+) int64 {
 	t.Helper()
 
-	result, err := New(Params{}).Process(t.Context(), bytes.NewReader(input), req)
+	result, err := New(Params{}).Process(t.Context(), bytes.NewReader(input), transform)
 	if err != nil {
 		t.Fatalf("Process() error = %v", err)
 	}
@@ -68,7 +71,8 @@ func TestImageProcessor_PNGIsCompressed(t *testing.T) {
 		}
 	}
 
-	size := processedSize(t, encodePNG(t, flat), &Request{Format: FormatPNG})
+	size := processedSize(t, encodePNG(t, flat),
+		&imagerequest.Transform{Format: imagerequest.FormatPNG})
 
 	const rawBytes = width * height * 3
 	if size > rawBytes/10 {
@@ -85,7 +89,8 @@ func TestImageProcessor_WebPAtEffort2(t *testing.T) {
 
 	input := createTestJPEG(t, 200, 150)
 
-	size := processedSize(t, input, &Request{Format: FormatWebP, Quality: 85})
+	size := processedSize(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatWebP, Quality: 85})
 
 	want, _, err := decode(t, input).ExportWebp(&vips.WebpExportParams{
 		StripMetadata:   true,
@@ -126,7 +131,8 @@ func TestImageProcessor_AVIFAtEffort1(t *testing.T) {
 
 	input := encodePNG(t, source)
 
-	size := processedSize(t, input, &Request{Format: FormatAVIF, Quality: 85})
+	size := processedSize(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatAVIF, Quality: 85})
 
 	want, _, err := decode(t, input).ExportAvif(&vips.AvifExportParams{
 		StripMetadata: true,
@@ -152,7 +158,8 @@ func TestImageProcessor_JPEGXLAtEffort4(t *testing.T) {
 
 	input := createTestJPEG(t, 200, 150)
 
-	size := processedSize(t, input, &Request{Format: FormatJXL, Quality: 85})
+	size := processedSize(t, input,
+		&imagerequest.Transform{Format: imagerequest.FormatJXL, Quality: 85})
 
 	params := vips.NewJxlExportParams()
 	params.Quality = 85