摊位收藏：常逛摊位的收藏回访

-- 错误：每次翻列表找摊，熟客也靠缘分
function findShop(shopId)
    for _, s in ipairs(shopList) do
        if s.id == shopId then return s end
    end
end

local favs = {}
local function toggleFav(shopId)
    for i, id in ipairs(favs) do
        if id == shopId then
            table.remove(favs, i)
            saveFavs(favs)
            return
        end
    end
    table.insert(favs, 1, shopId)
    if #favs > 20 then
        table.remove(favs)
    end
    saveFavs(favs)
end