Think about configs for domain and ports (possibly fan out other issues)

Just some considerations I thought of that I wanted to write down. Nothing urgent here.

Right now, the wallet sync server is on port 8090, and the external port for Caddy is 8091. Not only is the former is currently hard-coded in Go, the latter is as well for the purpose of links in registration emails. This works fine for us and probably most users. There are a few possible issues though:

1. The signup link in the email has an ugly :8091.
2. The server admin (not us) might want to run other services locally at :8090.
3. The server admin (not us) might want to run other services externally at :8091.

One thing we may consider for 1) is to have Caddy route the signup url specifically to port 443. Or maybe just serve the whole thing on port 443.

Though we need port 80 for ACME. The user might have stuff on port 80. I guess at that point it's on them to make their own Caddy config for all of it together.

For 2) we could have the internal port be configurable. We'd probably want it set in ansible since we'd have to set it to be the same in Go and Caddy/systemd configs. Maybe external port as well (for 3)), though there's less justification for that as a way to get around conflicts with other services, since we'll always need port 80 for ACME, and that's already a port they'll be likely having conflicts with.

The issue identifies hard-coded ports in Go and deployment concerns involving Ansible, Caddy, and systemd, but names no files or tests. Start by locating the port definitions and deployment configuration, then clarify whether the work should be split into separate issues. Done should mean an agreed configuration design for internal and external ports, signup links, and ACME constraints.