Per operator review on the PR: when the network module is on, the
matrix container's resolver is the dnsmasq in the gateway container, so
order the matrix container start after the gateway container. This is
robustness for tuwunel's lazy federation lookups, not a boot
requirement — the boot fix is the resolv.conf nameserver line (the
failure was a parse error on an empty resolv.conf, not connectivity).
Soft 'after' (not 'requires') keeps lifecycles decoupled; network.enable
asserts gateway.enable so the gateway container unit always exists.
43776afbfd