feat: rewrite K-factor engine with history tracking and outlier detection

Replace simple exponential smoothing with a rolling-average K-factor
system backed by a new auto_kfactor_history table. Budget fills are
detected and excluded from calculations, outliers beyond 2-sigma are
flagged, and confidence scores track data quality per customer.
Adds backfill endpoint, auto-create for missing estimation records,
and manual house_factor PUT endpoints for both auto and regular customers.

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

app/routers/fixstuff_customer.py

@@ -2,6 +2,7 @@ import logging
 from fastapi import APIRouter
 from fastapi.responses import JSONResponse
 from fastapi.encoders import jsonable_encoder
+from pydantic import BaseModel
 from database import session
 from sqlalchemy import func
 from datetime import date
@@ -27,6 +28,9 @@ TANK_MAX_FILLS = {
 }
 
 
+class HouseFactorUpdate(BaseModel):
+    house_factor: float
+
 
 router = APIRouter(
     prefix="/fixstuff_customer",
@@ -256,10 +260,32 @@ def estimate_customer_gallons_specific(customer_id: int):
     ).first()
 
     if not customer_estimate:
-        return JSONResponse(content={
-            "error": f"No fuel estimation data found for customer {customer_id}",
-            "solution": "Run the populate_estimates endpoint first to initialize customer data."
-        })
+        # Auto-create record from customer data
+        customer = session.query(Customer_Customer).filter(
+            Customer_Customer.id == customer_id
+        ).first()
+        if not customer:
+            return JSONResponse(content={"error": f"Customer {customer_id} not found"}, status_code=404)
+
+        customer_estimate = Customer_estimate_gallons(
+            customer_id=customer.id,
+            account_number=customer.account_number,
+            customer_town=customer.customer_town,
+            customer_state=customer.customer_state,
+            customer_address=customer.customer_address,
+            customer_zip=customer.customer_zip,
+            customer_full_name=f"{customer.customer_first_name} {customer.customer_last_name}".strip(),
+            estimated_gallons_left=Decimal('100'),
+            estimated_gallons_left_prev_day=Decimal('100'),
+            tank_size='275',
+            house_factor=Decimal('0.12'),
+            auto_status=1,
+            hot_water_summer=0
+        )
+        session.add(customer_estimate)
+        session.commit()
+        session.refresh(customer_estimate)
+        logger.info(f"Auto-created Customer_estimate_gallons record for customer {customer_id}")
 
     deliveries = session.query(Delivery).filter(
         Delivery.customer_id == customer_estimate.customer_id,
@@ -448,3 +474,25 @@ def populate_customer_estimates():
     }
 
     return JSONResponse(content=jsonable_encoder(result))
+
+
+@router.put("/house_factor/{customer_id}", status_code=200)
+def update_customer_house_factor(customer_id: int, body: HouseFactorUpdate):
+    logger.info(f"PUT /fixstuff_customer/house_factor/{customer_id}")
+    customer_estimate = session.query(Customer_estimate_gallons).filter(
+        Customer_estimate_gallons.customer_id == customer_id
+    ).first()
+
+    if not customer_estimate:
+        return JSONResponse(content={"error": "Customer estimate record not found"}, status_code=404)
+
+    customer_estimate.house_factor = Decimal(str(round(body.house_factor, 4)))
+    session.commit()
+    session.refresh(customer_estimate)
+
+    return JSONResponse(content=jsonable_encoder({
+        "id": customer_estimate.id,
+        "customer_id": customer_estimate.customer_id,
+        "house_factor": float(customer_estimate.house_factor),
+        "message": "House factor updated"
+    }), status_code=200)