Asset review pass: rework what the review flags

Go through the baked sprites with uo-client --asset-review (organic groups first: nature, world_flora, world_stone, then the rest), like or comment each one. Then rework every commented sprite under the shape-first rules (#105: clean slopes, ovals, smooth organic parts marked organic(), finish(snap=False)), re-bake it, and review it again (commented sprites come back once re-baked). Done when assets/reviews.jsonl has a like as the last verdict of every sprite in the manifests.