[Docs] Auto-generate model overview from registry.

[Pinaka07]

This PR makes the pytorch_forecasting model overview self-updating.

• Adds a small Sphinx extension (docs/source/_ext/model_overview.py) that
  writes models.rst from registry.all_objects(), including optional model tags
  and links to API docs.
• Wires the extension in conf.py and keeps a lightweight placeholder
  models.rst which is overwritten at build time.

Benefits

• No manual updates when models are added/renamed.
• Consistency with sktime’s estimator overview approach.
• Safe, fail-soft behavior if imports break (docs still build with a note).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1958   +/-   ##
=======================================
  Coverage        ?   87.24%           
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  Files           ?      143           
  Lines           ?     8896           
  Branches        ?        0           
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  Hits            ?     7761           
  Misses          ?     1135           
  Partials        ?        0           

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pytest	87.24% <ø> (?)

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[Pinaka07]

@fkiraly can you please tell me why the docs build is failing.

[fkiraly]

unsure, you can see the log here: https://app.readthedocs.org/api/v2/build/29355136.txt

It looks like import failures?

[Pinaka07]

@fkiraly Thanks for helping, I think the PR is ready to be merged. Can you please review it ?

[fkiraly]

hmm, seems like it does not work? This is how the file builds:

(it is on the doc build job - the "real" docs will look exactly the same if deployed)

[fkiraly]

there are no import failures, I think the page is simply not being overwritten as you intend?

[fkiraly]

hm, I think it still does not work? Have a look at how sktime does this (in docs/conf.py)

[fkiraly]

any ideas how to fix?

[Pinaka07]

any ideas how to fix?

Really sorry @fkiraly, as I was not able to respond. I am learning more about the sktime estimator overview and will update this code in a couple of days.

[fkiraly]

no problem! Looking forward to this, the model overview will be great!