feat: initial commit for oil price scraper service

FastAPI-based scraper for commodity ticker prices (HO, CL, RB futures)
and competitor oil pricing from NewEnglandOil. Includes cron-driven
scraping, PostgreSQL storage, and REST endpoints for price retrieval.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/database.py

@@ -0,0 +1,88 @@
+import logging
+import sys
+from contextlib import contextmanager
+from typing import Generator
+
+from sqlalchemy import create_engine, text
+from sqlalchemy.orm import sessionmaker, Session
+from sqlalchemy.exc import SQLAlchemyError
+
+from app.config import (
+    DATABASE_URL,
+    LOG_LEVEL,
+    LOG_FORMAT,
+)
+
+# =============================================================================
+# LOGGING CONFIGURATION
+# =============================================================================
+
+logging.basicConfig(
+    level=getattr(logging, LOG_LEVEL.upper(), logging.INFO),
+    format=LOG_FORMAT,
+    handlers=[
+        logging.StreamHandler(sys.stdout),
+    ]
+)
+logger = logging.getLogger(__name__)
+
+# =============================================================================
+# DATABASE SETUP
+# =============================================================================
+
+# Create SQLAlchemy engine with connection pooling
+engine = create_engine(
+    DATABASE_URL,
+    pool_pre_ping=True,  # Verify connections before use
+    pool_size=5,
+    max_overflow=10,
+    echo=False,  # Set to True for SQL debugging
+)
+
+# Session factory
+SessionLocal = sessionmaker(
+    autocommit=False,
+    autoflush=False,
+    bind=engine,
+)
+
+
+def get_db() -> Generator[Session, None, None]:
+    """
+    Dependency that provides a database session.
+
+    Yields a SQLAlchemy session and ensures proper cleanup.
+    """
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+@contextmanager
+def get_db_session() -> Generator[Session, None, None]:
+    """
+    Context manager for database sessions (non-dependency use).
+    """
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+def check_db_connection() -> bool:
+    """
+    Test database connectivity.
+
+    Returns:
+        True if database is reachable, False otherwise
+    """
+    try:
+        with get_db_session() as db:
+            db.execute(text("SELECT 1"))
+        return True
+    except SQLAlchemyError as e:
+        logger.error(f"Database connection failed: {e}")
+        return False