【后端接口】宠物进化：进化材料链与形态切换

local EVOLUTION_CHAIN = {
    { stage = 1, materials = { { "进化结晶", 5 } }, model = "pet_stage2" },
    { stage = 2, materials = { { "进化结晶", 10 }, { "龙之鳞片", 3 } }, model = "pet_stage3" },
}
function PetEvolve.run(actor, petIdx)
    local pet = actor:GetPet(petIdx)
    local nextStage = pet.stage + 1
    local chain = EVOLUTION_CHAIN[nextStage]
    if not chain then return false, "已达最终形态" end
    for _, mat in ipairs(chain.materials) do
        if getbagitemcount(actor, mat[1]) < mat[2] then
            return false, mat[1] .. " 不足"
        end
    end
    for _, mat in ipairs(chain.materials) do
        actor:TakeItemByName(mat[1], mat[2])
    end
    pet.stage = nextStage
    actor:UpdatePetModel(petIdx, chain.model)
    sendmsg(actor, 1, pet.name .. " 进化成功！")
    return true
end

function PetEvolve.recalcStats(pet)
    local baseAtk = PET_BASE[pet.race].atk
    local stageBonus = (pet.stage - 1) * 30
    pet.atk = baseAtk + stageBonus
    pet.hp = PET_BASE[pet.race].hp + stageBonus * 5
end