feat(docker)!: use scratch as base image

This change modifies the docker image so that it uses the scratch image instead of alpine. This is possible because the Vikunja binary is now entirely statically compiled, wich no dependencies on any system c libraries.

This also changes the default path for the sqlite file in the docker image (breaking). When using sqlite in docker, the VIKUNJA_DATABASE_PATH config variable or the file mount must be changed to prevent data loss.

Dockerfile

@@ -33,22 +33,14 @@ RUN export PATH=$PATH:$GOPATH/bin && \
 #  ┘└┘┘─┘┘└┘┘└┘┴─┘┘└┘
 
 # The actual image
-# Note: I wanted to use the scratch image here, but unfortunatly the go-sqlite bindings require cgo and
-# because of this, the container would not start when I compiled the image without cgo.
-FROM alpine:3.19 AS runner
+FROM scratch
 LABEL maintainer="maintainers@vikunja.io"
 WORKDIR /app/vikunja
-ENTRYPOINT [ "/sbin/tini", "-g", "--", "/entrypoint.sh" ]
+ENTRYPOINT [ "/app/vikunja/vikunja" ]
 EXPOSE 3456
+USER 1000
 
 ENV VIKUNJA_SERVICE_ROOTPATH=/app/vikunja/
-ENV PUID 1000
-ENV PGID 1000
-
-RUN apk --update --no-cache add tzdata tini shadow && \
-    addgroup vikunja && \
-    adduser -s /bin/sh -D -G vikunja vikunja -h /app/vikunja -H
-COPY docker/entrypoint.sh /entrypoint.sh
-RUN chmod 0755 /entrypoint.sh && mkdir files
+ENV VIKUNJA_DATABASE_PATH=/db/vikunja.db
 
 COPY --from=apibuilder /build/vikunja-* vikunja