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/salt-client/apply

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+# KNEL Salt Client Initializer
+# Configures Salt minion for configuration management
+
+set -euo pipefail
+
+echo "Running Salt client initializer..."
+
+# Configure Salt minion if configuration file exists
+if [[ -f ./configs/salt-minion ]]; then
+    cp ./configs/salt-minion /etc/salt/minion
+fi
+
+# Enable and start Salt minion service
+systemctl enable salt-minion
+systemctl start salt-minion
+
+echo "Salt client initializer completed"