snackpot.yml etc. - refine docker-compose config deploy

The main job of this commit:
- Be explicit about templates: expect the .j2 extension
- Copy all other files, so that they can be binary
- Don't deploy dotfiles or dotdirectories.

This snuck in:
- Remove `test` tag
- Refine some descriptions

templates/docker-compose/web.env.j2

@@ -0,0 +1,3 @@
+VIRTUAL_HOST={{ nextcloud_hostname }}
+LETSENCRYPT_HOST={{ nextcloud_hostname }}
+LETSENCRYPT_EMAIL={{ letsencrypt_email }}