【策划架构】Lua平表建树：沙巴克职级的父子装配

for _, row in ipairs(FLAT) do
    local parent = findNode(row.pid)   -- 每行都全表找父，平方级
    table.insert(parent.children, row)
end

local function buildTree(flat)
    local nodes = {}
    for _, r in ipairs(flat) do
        nodes[r.id] = {name = r.name, children = {}}
    end
    local root = {}
    for _, r in ipairs(flat) do
        if r.pid == 0 then
            root[#root + 1] = nodes[r.id]
        else
            local p = nodes[r.pid]
            p.children[#p.children + 1] = nodes[r.id]
        end
    end
    return root
end
sendmsg(actor, 1, "沙巴克职级树顶层 "
    .. #buildTree(FLAT) .. " 节点")