feat: add version constant and get_version() helper

src/__init__.py

@@ -7,8 +7,15 @@ from concurrent.futures import ThreadPoolExecutor  # noqa: E402
 
 from src.config import config as config  # noqa: E402
 
+__version__ = "0.5.0.dev"
+
 if os.getenv("YUXI_SKIP_APP_INIT") != "1":
     from src.knowledge import graph_base as graph_base  # noqa: E402
     from src.knowledge import knowledge_base as knowledge_base  # noqa: E402
 
 executor = ThreadPoolExecutor()  # noqa: E402
+
+
+def get_version():
+    """Return the Yuxi-Know version."""
+    return __version__