DOCS: Render API methods inline via custom autosummary templates (#847)

[priyam0k]

Summary of Changes

• Adds custom sphinx.ext.autosummary templates under docs/_templates/autosummary/: class.rst, class_inherited.rst, function.rst.
• API class pages now list methods and properties inline instead of a summary table that links to a separate page per method.
• Fixes the :template: names in docs/library/api.md to drop .rst (:template: class.rst → :template: class).
• Sets numpydoc_show_class_members = False and templates_path = ['_templates'] in docs/_config.yml (and the generated docs/conf.py).
• Guards docs/_ext/linkcode.py against property objects so inline members don't crash the build.

Three issues fixed along the way:

1. :template: class.rst never worked. Sphinx appends .rst, so it looked for autosummary/class.rst.rst and fell back to the base template. Names now omit the extension.
2. numpydoc duplicate table. numpydoc_show_class_members = False stops numpydoc emitting its own members table next to the inline members.
3. linkcode_resolve crash. Inline members pass property objects to the resolver, where inspect.getsourcefile(property) raises TypeError and aborts jb build. Fixed by unwrapping properties to fget and guarding getsourcefile / getsourcelines.

Related GitHub Issue(s)

• Closes [DOCS] create custom api doc templates #847
• Based on experimental; builds on merged docs: remove autosummary-generated API stubs #879.

Additional Context for Reviewers

• conf.py is regenerated from _config.yml by Jupyter Book; both updated to stay in sync.

• jb build . succeeds (warnings all pre-existing). HTML spot checks:

  Page	Inline methods	Inline properties	numpydoc table
  Development (class)	3	0	none
  Triangle (class_inherited)	64	24	none
  load_sample (function)	function block	–	–

One thing to decide: with :inherited-members: on, Triangle shows 64 methods and 24 properties, including sklearn ones it inherits like get_params, set_output, set_fit_request, get_metadata_routing. Do you want all of those shown, or should I hide the sklearn ones (or just drop inherited members entirely)? Let me know which you prefer and I'll adjust.

• Verified documentation changes locally with jb build . (HTML builder).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.04%. Comparing base (4ce0141) to head (74bde2c).
⚠️ Report is 1 commits behind head on experimental.

Additional details and impacted files

@@              Coverage Diff              @@
##           experimental     #885   +/-   ##
=============================================
  Coverage         87.04%   87.04%           
=============================================
  Files                86       86           
  Lines              4986     4986           
  Branches            646      646           
=============================================
  Hits               4340     4340           
  Misses              456      456           
  Partials            190      190           

Flag	Coverage Δ
unittests	87.04% <ø> (ø)

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