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/oam/apply

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# KNEL OAM Initializer
+# Sets up Operations and Maintenance tools
+
+set -euo pipefail
+
+echo "Running OAM initializer..."
+
+# Setup up2date script
+if [[ -f ./scripts/up2date.sh ]]; then
+    cp ./scripts/up2date.sh /usr/local/bin/up2date.sh
+    chmod +x /usr/local/bin/up2date.sh
+fi
+
+echo "OAM initializer completed"