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.

open-webui/README.md

@@ -40,7 +40,7 @@ connections exist the admin UI is where they change.
 
 | Volume | Mount | Holds |
 | --- | --- | --- |
-| `open-webui` | `/app/backend/data` | `webui.db`, uploads, the vector database, and model cache |
+| `open-webui-data` | `/app/backend/data` | `webui.db`, uploads, the vector database, and model cache |
 
 ## Image