epics2sms: include the running user in the startup notification

Add "by <user>" (effective user via id -un) to the startup message so
recipients can see who started the monitor.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

EPICS2SMS.sh

@@ -272,7 +272,7 @@ fi
 
 # Send a brief startup notification so recipients know the monitor is running
 # and what it watches. Best-effort: a failure here must not stop monitoring.
-startup_body="EPICS2SMS started $(date '+%F %T') on $(hostname -s), ${#pids[@]} monitor(s):"
+startup_body="EPICS2SMS started $(date '+%F %T') by $(id -un) on $(hostname -s), ${#pids[@]} monitor(s):"
 for line in "${summaries[@]}"; do
   startup_body+=$'\n'"- $line"
 done