refactor: Remove librenms, add ansible/salt clients

- Remove all librenms references from initializers and configuration
- Keep tailscale as requested (remove netbird plans)
- Add ansible-core (already present) and salt-minion packages
- Create salt-client initializer for minion configuration
- Update roles to replace librenms-agent with salt-client
- Simplify oam initializer to only handle up2date script
- Update README to reflect new architecture and tools

Prepares infrastructure for migration to Salt configuration management
while maintaining tailscale for VPN connectivity.

💘 Generated with Crush

Assisted-by: GLM-4.6 via Crush <crush@charm.land>

initializers/postfix/apply

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+# KNEL Postfix Module
+# Configures postfix for email delivery
+
+set -euo pipefail
+
+echo "Running postfix module..."
+
+# Stop postfix
+systemctl stop postfix
+
+# Configure postfix for local mail relay
+if [[ -f ./configs/postfix_generic ]]; then
+    cp ./configs/postfix_generic /etc/postfix/generic
+    postmap /etc/postfix/generic
+fi
+
+# Set postfix configuration
+postconf -e "inet_protocols = ipv4"
+postconf -e "inet_interfaces = 127.0.0.1"
+postconf -e "mydestination = 127.0.0.1"
+postconf -e "relayhost = tsys-cloudron.knel.net"
+postconf -e "smtp_generic_maps = hash:/etc/postfix/generic"
+
+# Restart postfix
+systemctl start postfix
+
+# Test mail delivery
+echo "Test email from $(hostname)" | mail -s "Test from $(hostname)" root
+
+echo "Postfix module completed"