```

chore: refactor logging module, update genesis timestamp, remove model relationships, and reorganize routers

- Rename logging.py to logger.py and update import paths in poa.py and main.py
- Update devnet genesis timestamp to 1766828620
- Remove SQLModel Relationship declarations from Block, Transaction, and Receipt models
- Add SessionDep type alias and get_session dependency in coordinator-api deps
- Reorganize coordinator-api routers: replace explorer/registry with exchange, users, marketplace

apps/coordinator-api/src/app/database.py

@@ -0,0 +1,17 @@
+"""Database configuration for the coordinator API."""
+
+from sqlmodel import create_engine, SQLModel
+from sqlalchemy import StaticPool
+
+# Create in-memory SQLite database for now
+engine = create_engine(
+    "sqlite:///:memory:",
+    connect_args={"check_same_thread": False},
+    poolclass=StaticPool,
+    echo=False
+)
+
+
+def create_db_and_tables():
+    """Create database and tables"""
+    SQLModel.metadata.create_all(engine)