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.