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.

.dockerignore

@@ -1,6 +1,7 @@
 files/
 dist/
 logs/
+docs/
 
 Dockerfile
 docker-manifest.tmpl