chore: fix __version__ runtime lie (2.0.0 -> 2.3.0)

Module-level __version__ declared 2.0.0 while pyproject.toml has
shipped 2.3.0 for months. Any integrator running
  import agent_passport; agent_passport.__version__
got the wrong number. Audit catch from 568ce4e flagged but
deferred. One-line correction; not 6b territory.

Author: aeoess

src/agent_passport/__init__.py

@@ -28,7 +28,7 @@
 Docs: https://aeoess.com/llms-full.txt
 """
 
-__version__ = "2.0.0"
+__version__ = "2.3.0"
 
 # Crypto
 from .crypto import generate_key_pair, sign, verify, public_key_from_private