fix(library): classify resolution by width + height, not height alone

Cinematic widescreen content (1920×804 at 2.39:1, 3840×1600 21:9, etc.)
was being misclassified: a 1080p source presented as 1920×804 fell to
720p because 804 < 900. Same shape for 2160p sources letterboxed below
2000px tall.

ResolveResolution now takes (width, height) and picks the larger of the
width-derived and height-derived buckets, so anamorphic/letterboxed
sources land in the right bucket.

internal/cmd/scan.go

@@ -241,7 +241,7 @@ func printScanSummary(cache *library.LibraryCache) {
 			continue
 		}
 
-		res := library.ResolveResolution(item.MediaInfo.Video.Height)
+		res := library.ResolveResolution(item.MediaInfo.Video.Width, item.MediaInfo.Video.Height)
 		if res == "" {
 			res = "other"
 		}