fix: silence default stderr logging via NullHandler (closes #36)

[Nexory]

Summary

Adds a NullHandler to the package's top-level logger so py_clob_client_v2 does not emit log records via Python's lastResort handler when the consuming application has not configured logging.

This is the standard library-logging pattern recommended in the Python logging cookbook:

"If a library user does not configure logging, and library code makes logging calls, then ... a one-off message 'No handlers could be found for logger X.Y.Z' is printed to the console."

Without this change, modules that log at ERROR (e.g. http_helpers/helpers.py:73 and :89, both prefixed [py_clob_client_v2]) print to stderr by default, which breaks curses-based terminal UIs and prevents callers from handling errors fully on their own.

Closes #36.

Change

import logging as _logging
_logging.getLogger(__name__).addHandler(_logging.NullHandler())

Added at the top of py_clob_client_v2/__init__.py before the public imports. The underscore on the import prevents from py_clob_client_v2 import * from re-exporting logging.

Behaviour

Caller's logging setup	Before this PR	After this PR
No logging configured	SDK errors print to stderr via lastResort	Silent
logging.basicConfig(...) configured	SDK errors go to user's handlers (unchanged)	SDK errors go to user's handlers (unchanged)
User opts in: logging.getLogger("py_clob_client_v2").setLevel(...)	Works	Works

Test plan

• Manual check: import py_clob_client_v2 in a fresh interpreter with no logging config; confirm no warning is printed.
• Manual check: configure root logger; confirm SDK errors still propagate to the configured handler.
• CI passes.

Happy to add a regression test in tests/ if maintainers prefer.