`Index.where(..., other)` should support `other` with more than array-like

[loicdiridollou]

Describe the bug
Right now Index.where(..., other=...) only supports the strict array-like (ExtensionArray and np.array), it seems that having Series or Index works at runtime and makes sense.

To Reproduce

1. Provide a minimal runnable pandas example that is not properly checked by the stubs.
2. Indicate which type checker you are using (mypy or pyright).
3. Show the error message received from that type checker while checking your example.

import pandas as pd
import numpy as np

datetime_index = pd.DatetimeIndex(pd.date_range(start="2025-01-01", freq="h", periods=48))
mask = np.ones(48, dtype=bool)

condition = datetime_index.where(mask,datetime_index - pd.Timedelta(days=1))

It yields the following error:

Argument 2 to "where" of "Index" has incompatible type "DatetimeIndex"; expected "str | bytes | date | datetime | timedelta | <13 more items> | None"  [arg-type]

Please complete the following information:

• OS: MacOS
• OS Version 26
• python version 3.13
• version of type checker 1.18.1
• version of installed pandas-stubs main

Additional context
Add any other context about the problem here.

[Dr-Irv]

Interestingly, the docs for Series.where say "scalar, Series/DataFrame, or callable" for the other argument, where Index.where has scalar, or array-like,

Looking at the tests in pandas, Index and Series are not tested. So I think an issue should be raised in the pandas repo, whether support of Series and Index is desired or not, or whether the docs need to be updated.

[loicdiridollou]

Asked the pandas team in pandas-dev/pandas#62646