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 CBOR field names, so tokens made before still decode. 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/imgcache/cache_internal_test.go

@@ -10,6 +10,7 @@ import (
 
 	_ "modernc.org/sqlite"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 func setupTestDB(t *testing.T) *sql.DB {
@@ -117,13 +118,17 @@ func TestCache_LookupMiss(t *testing.T) {
 	cache := setupTestCache(t)
 	ctx := context.Background()
 
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: testPathCat,
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testHostCDN,
+			Path: testPathCat,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 800, Height: 600},
+			Format:  imagerequest.FormatWebP,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 
 	result, err := cache.Lookup(ctx, req)
@@ -146,13 +151,17 @@ func TestCache_StoreAndLookup(t *testing.T) {
 	cache := setupTestCache(t)
 	ctx := context.Background()
 
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: testPathCat,
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testHostCDN,
+			Path: testPathCat,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 800, Height: 600},
+			Format:  imagerequest.FormatWebP,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 
 	// Store source content
@@ -173,7 +182,7 @@ func TestCache_StoreAndLookup(t *testing.T) {
 	}
 
 	// Store variant
-	cacheKey := CacheKey(req)
+	cacheKey := imagerequest.CacheKey(req)
 	outputContent := []byte("fake webp data")
 
 	err = cache.StoreVariant(
@@ -207,11 +216,15 @@ func TestCache_NegativeCache(t *testing.T) {
 	cache := setupTestCache(t)
 	ctx := context.Background()
 
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/notfound.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testHostCDN,
+			Path: "/photos/notfound.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 800, Height: 600},
+			Format: imagerequest.FormatWebP,
+		},
 	}
 
 	// Store negative cache entry
@@ -248,11 +261,15 @@ func TestCache_NegativeCacheExpiry(t *testing.T) {
 
 	ctx := context.Background()
 
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/expired.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testHostCDN,
+			Path: "/photos/expired.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 800, Height: 600},
+			Format: imagerequest.FormatWebP,
+		},
 	}
 
 	// Store negative cache entry
@@ -281,17 +298,21 @@ func TestCache_VariantLookup(t *testing.T) {
 	cache := setupTestCache(t)
 	ctx := context.Background()
 
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/variant.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testHostCDN,
+			Path: "/photos/variant.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 800, Height: 600},
+			Format:  imagerequest.FormatWebP,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 
 	// Store variant
-	cacheKey := CacheKey(req)
+	cacheKey := imagerequest.CacheKey(req)
 	outputContent := []byte("output data")
 
 	err := cache.StoreVariant(
@@ -331,17 +352,21 @@ func TestCache_GetVariant_ReturnsContentType(t *testing.T) {
 	cache := setupTestCache(t)
 	ctx := context.Background()
 
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/variantct.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testHostCDN,
+			Path: "/photos/variantct.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 800, Height: 600},
+			Format:  imagerequest.FormatWebP,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 
 	// Store variant
-	cacheKey := CacheKey(req)
+	cacheKey := imagerequest.CacheKey(req)
 	outputContent := []byte("output webp data")
 
 	err := cache.StoreVariant(
@@ -383,17 +408,21 @@ func TestCache_GetVariant(t *testing.T) {
 	cache := setupTestCache(t)
 	ctx := context.Background()
 
-	req := &ImageRequest{
-		SourceHost: testHostCDN,
-		SourcePath: "/photos/output.jpg",
-		Size:       Size{Width: 800, Height: 600},
-		Format:     FormatWebP,
-		Quality:    85,
-		FitMode:    FitCover,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: testHostCDN,
+			Path: "/photos/output.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: 800, Height: 600},
+			Format:  imagerequest.FormatWebP,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 
 	// Store variant
-	cacheKey := CacheKey(req)
+	cacheKey := imagerequest.CacheKey(req)
 	outputContent := []byte("the actual output content")
 
 	err := cache.StoreVariant(