Harden the four monitoring scripts

set -euo pipefail across all four, but added deliberately rather than
pasted in -- each script needed the places where a non-zero exit is
normal handled first, or strict mode would have made them worse:

- sys_monitor / process_monitor: `ps | head -n 6` is a latent SIGPIPE.
  head closes the pipe after six lines, and on a host with enough
  processes ps fills the buffer and exits 141, which pipefail turns into
  a script abort -- on exactly the busy machine you wanted to inspect.
  Confirmed the mechanism (a large producer into head returns 141) and
  those pipelines now tolerate it.
- security_audit: find exits non-zero when it cannot read a directory,
  which is routine when walking the whole filesystem. Without handling,
  set -e aborted the audit part way while still looking complete. Also
  notes that a clean report as non-root means little, since find cannot
  descend where it may not read.
- network_info: iptables needs root, so the last section aborted the
  script for ordinary users. Now reports the failure, and falls back to
  nft where iptables is absent.

process_monitor also no longer kills on sight. `pkill -x` by name can
match several processes at once, and as root that is an easy way to take
down more than intended. It now prints what it matched and asks, with
FORCE=1 for unattended use and a refusal rather than a hang when there
is no tty.

All four run clean; the kill path was tested against a live process and
left it alive.

network_info.sh

@@ -17,7 +17,12 @@
 # 
 # Usage: network_info.sh    (no arguments)
 # Description: Displays network interface addresses, routing table, open ports, and iptables rules.
- 
+#
+# Read-only. The iptables section needs root; without it that section
+# reports the failure rather than silently showing nothing.
+
+set -euo pipefail
+
 echo "==== Network Interfaces (IP addresses) ===="
 if command -v ip &> /dev/null; then
   ip -brief addr show    # brief output of interfaces and addresses
@@ -47,7 +52,10 @@ fi
 
 echo -e "\n==== Firewall Rules (iptables) ===="
 if command -v iptables &> /dev/null; then
-  iptables -L -n -v    # list firewall rules with numeric addresses and packet counts
+  # Needs root; report the failure instead of letting set -e abort here.
+  iptables -L -n -v || echo "Could not read iptables rules (run as root?)."
+elif command -v nft &> /dev/null; then
+  nft list ruleset || echo "Could not read nftables ruleset (run as root?)."
 else
   echo "iptables command not found (no firewall rules to show or using nftables)."
 fi