Attempt at caddyfile/proxy, simplification

The idea of proxying in front of Garage may be warranted, to handle some
of the ways that it subdomains further. However, I'm not there yet.

Dockerfile

@@ -1,5 +1,8 @@
 FROM cloudron/base:5.0.0
 
+RUN apt-get update ; apt-get install -y \
+  caddy
+
 # Garage wants these directories for storing stuff.
 # We want it here so that /app/data gets backed up.
 RUN mkdir -p /app/data/garage/data /app/data/garage/meta
@@ -8,6 +11,8 @@ ADD https://garagehq.deuxfleurs.fr/_releases/v2.1.0/x86_64-unknown-linux-musl/ga
 RUN chmod 755 /usr/bin/garage
 
 COPY garage.toml /garage/garage.toml
+COPY caddyfile /garage/caddyfile
+
 # Create a symlink that will become dead; we'll fill it again 
 # with the startup script.
 RUN ln -s /app/data/garage.toml /etc/garage.toml