[DOC] Migrate docstrings in models/timexer/ to numpydoc format

[sohamjadhav95]

Description

The pytorch_forecasting/models/timexer/ module still has Google-style docstrings (Args: / Returns:) across multiple files. As part of the ongoing numpydoc migration (#2066), I'd like to convert all remaining files in this module.

Files affected

• pytorch_forecasting/models/timexer/_timexer.py: 10 docstrings
• pytorch_forecasting/models/timexer/sub_modules.py: 8 docstrings
• pytorch_forecasting/models/timexer/_timexer_v2.py: 4 docstrings

What I'll do

• Convert all Args: blocks to Parameters\n----------
• Convert all Returns: blocks to Returns\n-------
• No logic changes, documentation only

Related

Part of the broader numpydoc migration: #2066

[sohamjadhav95]

@phoeenniixx @fkiraly
I'll come up with all the fixes at earliest.