False postive "list[Self@Baz]" is not assignable to "list[Baz]" with `ClassVar` assignment

Code sample in [pyright playground](https://pyright-play.net/?code=GYJw9gtgBALgngBwJYDsDmUkQWEMoDCANgIYDOZAaiSADRQDKApkcAFBsDGpFUAQiQBeALjZRxhADIMA%2BpQCCAJWGEeVGgG0iSMjA3NWAXUMcBggHQFpcpVAC8UDYfEBiKAFEQ4EFAD8AQjYzS2sFRXMSBAQmFAATAAozeIBKZNcoAHkAaQ5ucjIoADEwMFEJKVkwlWJ86hAtHT0DYGN7R2coN2yOYrAQyqUIqJiE3pS0zsycrjV%2BGjKJKwHlVVrNbV19FhaTIJp%2Bm0U2jQEQFI6unKA)

```python
from typing import ClassVar, Self

class Baz:
CLS_VAR: ClassVar[list[Self]]

Baz.CLS_VAR = [] # Error ?!
Baz.CLS_VAR.append(Baz()) # OK

class Foo:
CLS_VAR: ClassVar[list[Self]] = [] # OK

Foo.CLS_VAR.append(Foo()) # OK

class Bar:
CLS_VAR: ClassVar[list[Self]]

Bar.CLS_VAR = [Bar()] # OK
```

Reproduce the diagnostic in the linked Pyright playground using the Baz, Foo, and Bar examples, then trace the ClassVar and Self assignment analysis that distinguishes them. Done means the Baz assignment no longer reports an incompatibility while the valid examples remain accepted, with regression coverage for the demonstrated cases.

Written by the indexing model from the issue text.