vararg overload issue

If you have a function which takes in only a vararg and you only overload it, the input type is as expected just each of the overloads:

---@overload fun(param1: "test", param2: string)
---@overload fun(param1: "test2", param2: number)
---@overload fun(param1: "test3", param2: boolean, param3: number)
local function test(...)
end

test()

However, if you have a param before the vararg, the input type always becomes param, ...any:

---@overload fun(param1: "test", param2: string)
---@overload fun(param1: "test2", param2: number)
---@overload fun(param1: "test3", param2: boolean, param3: number)
local function test(param1, ...)
end

test()

先重現 issue 中標註的兩個 Lua 範例，並比較兩種 vararg 形式推導出的簽章。追蹤 overload 和 vararg 型別處理的進入點，接著確認參數位於 vararg 之前的情況會保留 overload 特定的參數型別，而不是將其合併為 ...any。