Change how server logs are dumped

Currently it dumps server logs to stdout and only on failure. This can always be spat out if `COMPLEMENT_ALWAYS_PRINT_SERVER_LOGS=1`. However, this isn't the most discoverable, as both Erik and vdh asked me how to get server logs from Complement in the same day.

It would be better if:
- we always printed server logs,
- to disk,
- based on the hs name,
- and then removed `COMPLEMENT_ALWAYS_PRINT_SERVER_LOGS`.

For extra discoverability, indicating that server logs are going to file X would be useful.

This would be a breaking change to the Complement API.

Start by tracing Complement's current server-log handling and the COM​PLEMENT_ALWAYS_PRINT_SERVER_LOGS=1 behavior. Define how logs should be written to disk using the hs name, how the destination is reported, and how the breaking API change affects callers. Done means logs are always written and discoverable without the environment variable.

Written by the indexing model from the issue text.