TC-1012: deploy: serve the node through dstack-ingress only

[samgbafa]

• Removes the tinycloud host port mapping from docker-compose.dstack-postgres.yaml; dstack-ingress still reaches the node on the compose network.
• docker.yml: pre-deploy check of the node.tinycloud.xyz worker route, and a post-deploy check that the node answers only via the ingress.
• Before merging: deploy the worker change (samgbafa/tinycloud-dev#83) and the TinyFeed host change first; confirm the 32 MiB ingress upload limit for node.tinycloud.xyz. Needs a deploy window and Sam's go-ahead.
• Test steps and deploy notes: https://linear.app/tinycloud-labs/issue/TC-1012#comment-3bbc0ff8

https://linear.app/tinycloud-labs/issue/TC-1012

[samgbafa]

Superseded by #317 (the node 95 MiB body cap) and tinycloud-dev #135 (the Worker cap); the ingress-only route was dropped in favour of the approved fast route. See TC-1012.