feat(ui): increase cover art size to 600px and use CatmullRom scaling

Increased the UI cover art request size from 300px to 600px for sharper
images on high-DPI displays. Replaced BiLinear with CatmullRom (bicubic)
interpolation for higher quality image resizing. Extracted the hardcoded
size into a COVER_ART_SIZE constant in the frontend and consolidated
backend sizes into a CacheWarmerImageSizes slice. Removed the unused
UIThumbnailSize constant.

Signed-off-by: Deluan <deluan@navidrome.org>

core/artwork/cache_warmer.go

@@ -142,15 +142,14 @@ func (a *cacheWarmer) doCacheImage(ctx context.Context, id model.ArtworkID) erro
 	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
 	defer cancel()
 
-	for _, size := range []int{consts.UICoverArtSize, consts.UIThumbnailSize} {
+	for _, size := range consts.CacheWarmerImageSizes {
 		r, _, err := a.artwork.Get(ctx, id, size, true)
 		if err != nil {
 			return fmt.Errorf("caching id='%s', size=%d: %w", id, size, err)
 		}
-		defer r.Close()
-		if _, err = io.Copy(io.Discard, r); err != nil {
-			return err
-		}
+		_, err = io.Copy(io.Discard, r)
+		r.Close()
+		return err
 	}
 	return nil
 }

core/artwork/cache_warmer_test.go

@@ -176,13 +176,13 @@ var _ = Describe("CacheWarmer", func() {
 			}).Should(Equal(0))
 		})
 
-		It("pre-caches both UICoverArtSize and UIThumbnailSize", func() {
+		It("pre-caches UICoverArtSize", func() {
 			cw := NewCacheWarmer(aw, fc).(*cacheWarmer)
 			cw.PreCache(model.MustParseArtworkID("al-1"))
 
 			Eventually(func() []int {
 				return aw.getCachedSizes()
-			}).Should(ContainElements(consts.UICoverArtSize, consts.UIThumbnailSize))
+			}).Should(ContainElements(consts.UICoverArtSize))
 		})
 	})
 })

core/artwork/reader_playlist.go

@@ -264,6 +264,6 @@ func fillCenter(src image.Image, dstW, dstH int) image.Image {
 	}
 
 	dst := image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
-	xdraw.BiLinear.Scale(dst, dst.Bounds(), src, cropRect, draw.Src, nil)
+	xdraw.CatmullRom.Scale(dst, dst.Bounds(), src, cropRect, draw.Src, nil)
 	return dst
 }

core/artwork/reader_resized.go

@@ -155,7 +155,7 @@ func resizeStaticImage(data []byte, size int, square bool) (io.Reader, int, erro
 		dst = image.NewNRGBA(image.Rect(0, 0, dstW, dstH))
 		dstRect = dst.Bounds()
 	}
-	xdraw.BiLinear.Scale(dst, dstRect, original, bounds, draw.Src, nil)
+	xdraw.CatmullRom.Scale(dst, dstRect, original, bounds, draw.Src, nil)
 
 	buf := bufPool.Get().(*bytes.Buffer)
 	buf.Reset()