BetterPets-Paper

Fix: Scrapped skins are reliably collected

The unlock relied on a hidden variant tag on the item. Some items (older ones, or certain paths) carry the variant head but not the tag, so scrapping them collected nothing — which is why a skin sometimes did not show up in Customize.

• Scrapping now recovers the skin from the item's head texture when the tag is missing, so any visibly-skinned pet item collects the right skin.
• Scrapping a single pet now always tells you the result: unlocked X (new) or you already own X. (Console debug logs when an item has no resolvable skin.)
• The catalogue variant gallery now marks which skins you have ✔ Collected (with a glint) vs Not collected yet — per player, even for pets you do not own.

Compiles clean on Paper 26.2; 63/63 tests pass. Drop BetterPets-1.17.4.jar into your plugins/ folder.