Services now print RFC 5424 to stdout; Docker captures via json-file driver.
A new host-side collector (decnet.web.collector) streams docker logs from all
running decky service containers and writes RFC 5424 + parsed JSON to the host
log file. The existing ingester continues to tail the .json file unchanged.
rsyslog can consume the .log file independently — no DECNET involvement needed.
Removes: bind-mount volume injection, _LOG_NETWORK bridge, log_target config
field and --log-target CLI flag, TCP syslog forwarding from service templates.
