feat(help): header-driven --help for system-info functions

gip, gip4, gip6, ports, swapstat, sbver and steam-dl. All ignored $argv,
so --help previously ran the query or the launcher. sbver keeps its own
--brief flag: only argv[1] is inspected and --brief is not a help flag,
so the body still runs for it.

functions/swapstat.fish

@@ -15,6 +15,8 @@
 # EXAMPLE
 #   swapstat
 function swapstat --description 'View colorized zRAM and swappiness status'
+    __fish_help_header (status current-function) $argv; and return 0
+
     set -l swappiness (sysctl -n vm.swappiness)
     set -l zdata (zramctl --bytes --noheadings --output DATA,TOTAL /dev/zram0 2>/dev/null)