Sixth and last of the modules that were the link rather than this
product. main.rs loses config_home, data_home and xdg_dir, and its test
module with them -- it held one test, which moved to the crate that now
holds the code.
The helpers gained a `product` parameter, matching certs::ensure and
netif::wg_address, which is what keeps two products' state apart while
resolving it identically.
Verified by running it: with only XDG_CONFIG_HOME and XDG_DATA_HOME set
and no --config or --data-dir, the server puts its certificates in
$XDG_CONFIG_HOME/ai-app/certs and its sessions in
$XDG_DATA_HOME/ai-app/sessions, and still prints an aiapp:// enrollment
URI. 35 tests here and 19 in the crate, clippy silent, rustfmt clean.
iris
2c925a679f