Add email notifications (sendmail) + membership sweep (scheduler): welcome email on webhook, reconcile endpoint, daily sweep

Dockerfile

@@ -8,6 +8,8 @@ RUN pip install --no-cache-dir -r requirements.txt
 
 # Copy app
 COPY app/ ./app/
+COPY sweep.sh /app/code/sweep.sh
+RUN chmod +x /app/code/sweep.sh
 
 # Run as root (the base image default). Cloudron's sandboxing (read-only
 # rootfs, AppArmor, dropped capabilities) still applies to root inside the