chore: initialize monorepo with project scaffolding, configs, and CI setup

apps/blockchain-node/src/aitbc_chain/database.py

@@ -0,0 +1,20 @@
+from __future__ import annotations
+
+from contextlib import contextmanager
+
+from sqlmodel import Session, SQLModel, create_engine
+
+from .config import settings
+
+_engine = create_engine(f"sqlite:///{settings.db_path}", echo=False)
+
+
+def init_db() -> None:
+    settings.db_path.parent.mkdir(parents=True, exist_ok=True)
+    SQLModel.metadata.create_all(_engine)
+
+
+@contextmanager
+def session_scope() -> Session:
+    with Session(_engine) as session:
+        yield session