Add Horse, Rabbit, Guinea Pig, Hamster, Mouse, Rat, Snake, Lizard, Turtle,
Gecko, and Spider as Species (with breed taxonomies + DE translations),
alongside the existing Dog/Cat/Bird. The species/breed system was already
fully data-driven (pet creation, onboarding, ad targeting all read
pets.listSpecies/listBreeds dynamically), so this is mostly seed data.
Spiders get dedicated handling: an opt-in Owner.hideSpiders preference
(offered once during onboarding via ArachnophobiaOptIn, always
re-toggleable on /pets via HideSpidersToggle) fully excludes Species=Spider
pets/posts from feed, explore, and search when enabled.