Add documentations for developers on how this package supports static typing.

[junkmd]

Summary

• CONTRIBUTING.md
  Added details about the CI pipeline: it now runs static type checking (mypy, pyright, ty) in addition to runtime tests, and clarifies that urgent releases may proceed even if type checks fail.
• docs/source/index.rst
  Added a reference to the new type_checking.rst section in the documentation index.
• docs/source/type_checking.rst
  Introduced a new documentation page that explains how comtypes generates type hints, provides a detailed example using Scripting.Dictionary, and discusses limitations of static type analysis for COM pointers.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.98%. Comparing base (715ab82) to head (4dcfcc2).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #953   +/-   ##
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  Coverage   88.98%   88.98%           
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  Files         140      140           
  Lines       13678    13678           
=======================================
  Hits        12171    12171           
  Misses       1507     1507           

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