feat: Business Central backup Docker container with web management panel

Python backup module (Azure AD OAuth2 → BC API v2.0 → GPG AES256 → S3),
Flask web UI on port 1890 with SSE live log streaming, dual incremental +
full backup schedules, chain restore merging full + incrementals, and
per-entity file browser with ZIP download.

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

Dockerfile

@@ -0,0 +1,18 @@
+FROM python:3.11-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends gnupg \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY backup_bc.py web.py ./
+COPY templates/ templates/
+
+VOLUME ["/data"]
+ENV BCBAK_DATA=/data
+ENV PORT=1890
+EXPOSE 1890
+
+CMD ["python", "web.py"]