Fix math review findings (#826 Redmine note follows)

- constants drift: CURRENT_MONTHLY_BILL 301.08->264.47, CURRENT_ANNUAL_CONSUMPTION 23952->22614 (15-month billing table is truth)
- plan header: ROI 9.1 -> 10.2 yrs (matches table); 14% -> 26.6% kWh / 12.7% bill offset
- Dockerfile entrypoint ran DEPRECATED solar_estimate.py (400W panels); now runs the current bash analyzer on alpine
- scenario payback caveat: fixed $4,100 cost across array sizes = optimistic ceilings

https://projects.knownelement.com/issues/826#note-1

solar-analysis/Dockerfile

@@ -1,9 +1,13 @@
-FROM python:3.11-slim
+# SITER-Solar analysis container — runs the CURRENT bash analyzer.
+# (2026-09-06, #826: entrypoint previously ran the DEPRECATED
+# solar_estimate.py, which also assumed 400W panels. Retired.)
+FROM alpine:3.20
+
+RUN apk add --no-cache bash curl jq bc
 
 WORKDIR /app
 
-RUN pip install --no-cache-dir requests
+COPY siter-solar-analysis.sh /app/siter-solar-analysis.sh
+RUN chmod +x /app/siter-solar-analysis.sh
 
-COPY solar_estimate.py /app/
-
-ENTRYPOINT ["python", "solar_estimate.py"]
+ENTRYPOINT ["/app/siter-solar-analysis.sh"]