Migrate exchange app to centralized aitbc package utilities

- Migrate 2 files from logging to aitbc.get_logger
- health_monitor.py, real_exchange_integration.py
- Remove logging.basicConfig() from both files
- Migrate 3 files with hardcoded paths to use DATA_DIR constant
- simple_exchange_api.py, scripts/seed_market.py, database.py

apps/exchange/database.py

@@ -7,10 +7,11 @@ import os
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker, Session
 from sqlalchemy.pool import StaticPool
+from aitbc.constants import DATA_DIR
 from models import Base
 
 # Database configuration
-DATABASE_URL = os.getenv("EXCHANGE_DATABASE_URL", "sqlite:////var/lib/aitbc/data/exchange/exchange.db")
+DATABASE_URL = os.getenv("EXCHANGE_DATABASE_URL", f"sqlite:///{DATA_DIR}/data/exchange/exchange.db")
 
 # Create engine
 if DATABASE_URL.startswith("sqlite"):