Add comprehensive docstrings and configure Sphinx autodoc

- Added detailed NumPy-style docstrings to all public methods in Presence and AioPresence classes
- Added detailed NumPy-style docstrings to all public methods in Client and AioClient classes
- Added comprehensive docstrings to BaseClient class
- Enhanced ActivityType and StatusDisplayType enum documentation
- Updated Sphinx conf.py to enable autodoc, napoleon, and configure sys.path
- Converted presence.rst and client.rst to use autodoc directives
- Documentation now automatically generated from Python docstrings
- All tests pass successfully
- Documentation builds without errors

Co-authored-by: kaneryu <72762358+kaneryu@users.noreply.github.com>

Author: Copilot

docs/sphinx/_build/.buildinfo

@@ -0,0 +1,4 @@
+# Sphinx build info version 1
+# This file records the configuration used when building these files. When it is not found, a full rebuild will be done.
+config: d6f33dc84547be0a880fffd514e2620c
+tags: 645f666f9bcd5a90fca523b33c5a78b7