feat(CRIT-010): add zone-to-county mapping and county_id to oil_prices

Add ZONE_COUNTY_MAP for all 5 scraped states (42 zone-to-county entries).
Scraper now resolves county_id at startup and assigns it to each record.
Upsert logic deduplicates by (name, state, county_id) to prevent duplicates
when multiple zones map to the same county. Also adds County model for
DB lookups and fixes Rhode Island zone count (4, not 5).

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

fuel_scraper/db_operations.py

@@ -0,0 +1,105 @@
+"""
+Database operations module for oil price CRUD operations.
+"""
+import logging
+from datetime import datetime
+from sqlalchemy.orm import Session
+
+import sys
+import os
+# Add parent directory to path for imports
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+import models
+
+
+def upsert_oil_price(db_session: Session, item_dict: dict) -> bool:
+    """
+    Insert or update an oil price record.
+
+    Logic:
+    - Match by (name, state, county_id) when county_id is available to avoid
+      duplicates when multiple zones map to the same county.
+    - Fall back to (name, state, zone) when county_id is not available.
+    - If record exists with non-null company_id: skip (vendor-managed price)
+    - If record exists with null company_id and different price: update
+    - If record exists with same price: skip (no change)
+    - If no record exists: insert new
+
+    Args:
+        db_session: SQLAlchemy session
+        item_dict: Dictionary with state, zone, name, price, date, county_id
+
+    Returns:
+        True if a record was inserted or updated, False otherwise
+    """
+    county_id = item_dict.get("county_id")
+
+    # Check if record already exists - prefer matching by county_id to avoid
+    # duplicates when multiple zones map to the same county
+    if county_id is not None:
+        existing_record = db_session.query(models.OilPrice).filter(
+            models.OilPrice.name == item_dict["name"],
+            models.OilPrice.state == item_dict["state"],
+            models.OilPrice.county_id == county_id
+        ).first()
+    else:
+        existing_record = db_session.query(models.OilPrice).filter(
+            models.OilPrice.name == item_dict["name"],
+            models.OilPrice.state == item_dict["state"],
+            models.OilPrice.zone == item_dict["zone"]
+        ).first()
+
+    if existing_record:
+        # Record exists - check if we should update
+        if existing_record.company_id is not None:
+            logging.debug(
+                f"Skipping update for {item_dict['name']} in {item_dict['state']} zone {item_dict['zone']} "
+                "due to non-null company_id"
+            )
+            return False
+
+        # Always update county_id if we have one and it differs
+        updated = False
+        if county_id is not None and existing_record.county_id != county_id:
+            existing_record.county_id = county_id
+            updated = True
+
+        # Company ID is null - check if price changed
+        if existing_record.price != item_dict["price"]:
+            existing_record.price = item_dict["price"]
+            existing_record.date = item_dict["date"]
+            existing_record.scrapetimestamp = datetime.utcnow()
+            logging.info(
+                f"Updated price for {item_dict['name']} in {item_dict['state']} zone {item_dict['zone']} "
+                f"to {item_dict['price']}"
+            )
+            return True
+        elif updated:
+            existing_record.scrapetimestamp = datetime.utcnow()
+            logging.info(
+                f"Updated county_id for {item_dict['name']} in {item_dict['state']} zone {item_dict['zone']} "
+                f"to {county_id}"
+            )
+            return True
+        else:
+            logging.debug(
+                f"Price unchanged for {item_dict['name']} in {item_dict['state']} zone {item_dict['zone']}"
+            )
+            return False
+    else:
+        # No record exists - create new
+        oil_price_record = models.OilPrice(
+            state=item_dict["state"],
+            zone=item_dict["zone"],
+            name=item_dict["name"],
+            price=item_dict["price"],
+            date=item_dict["date"],
+            county_id=county_id,
+            scrapetimestamp=datetime.utcnow()
+        )
+        db_session.add(oil_price_record)
+        logging.info(
+            f"Added new record for {item_dict['name']} in {item_dict['state']} zone {item_dict['zone']} "
+            f"(county_id={county_id})"
+        )
+        return True