`assign-type-mismatch` warning when overloading a derived class

Nobody has claimed this yet.

### How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

### Which OS are you using?

Windows

### What is the issue affecting?

Annotations, Type Checking, Diagnostics/Syntax Checking

### Expected Behaviour

No warning generated.

### Actual Behaviour

An `assign-type-mismatch` warning is thrown.

### Reproduction steps

```lua
---@class Parent

---@return Parent
local function newParent() local o = {}; return setmetatable(o, o) end

---@class Object : Parent
---@overload fun(s: string) -- Or disable the diagnostic on this line
local o = newParent() -- Invalid warning here

function o:__call() end
```

### Additional Notes

The overload workaround, mentioned in #1733 does not work in this use case. A function returns a type, from which a new class is created. When overloading this new class, an invalid warning is generated.

ℹ️ A workaround I've found is to make the class derive also from `table`:
```diff
- ---@class Parent
+ ---@class Parent : table
```

### Log File

_No response_

Reproduce the warning from the Lua snippet in the Visual Studio Code extension, focusing on the `assign-type-mismatch` diagnostic when `@overload` is applied to a class returned by a function. Trace the handling of `@class` inheritance and overloads, then verify that the reproduction no longer emits the invalid warning while preserving the documented `table` workaround behavior.

Written by the indexing model from the issue text.