Add IneffectiveLeaseWarning and IneffectiveQuorumTimeoutWarning to wool.__all__

[conradbzura]

Description

Re-export IneffectiveLeaseWarning (defined in wool.runtime.worker.pool) and IneffectiveQuorumTimeoutWarning (defined in wool.runtime.worker.proxy) from wool/__init__.py, and add both names to wool.__all__. Place them on the public package surface beside SerializationWarning, under the WoolWarning umbrella.

Motivation

Both warnings are user-tunable through the standard warnings filter — warnings.filterwarnings("error", category=...) or PYTHONWARNINGS=error::wool.IneffectiveLeaseWarning — but neither has a stable public import path. A caller who wants to silence, promote, or filter one must reach into a private module: from wool.runtime.worker.pool import IneffectiveLeaseWarning. That couples application code to Wool's internal layout. SerializationWarning already sits on the package surface; these two belong there too.

Expected Outcome

• from wool import IneffectiveLeaseWarning, IneffectiveQuorumTimeoutWarning resolves.
• Both names appear in wool.__all__, beside SerializationWarning, and the public-API allowlist test covers them.
• The emission sites in pool.py and proxy.py are untouched — no behavior change.