refactor: name supporting services and volumes by role

Rename database services to db and cache services to cache, with their
volumes as db-data and cache-data, in litellm, owncloud and goclaw. Rename
the couchbase and open-webui volumes to <service>-data. Data on miti-sg was
copied into the new volumes beforehand; the old volumes are kept.

couchbase/README.md

@@ -19,4 +19,4 @@ The admin console is on `8091`. Complete the first-run setup there.
 
 ## Storage
 
-`couchbase_data` at `/opt/couchbase/var` — data, indexes, config, logs.
+`couchbase-data` at `/opt/couchbase/var` — data, indexes, config, logs.