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/scripts/up2date.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+echo "Running apt-get update"
+export DEBIAN_FRONTEND="noninteractive" && apt-get -qq --yes update
+
+echo "Running apt-get dist-upgrade"
+export DEBIAN_FRONTEND="noninteractive" && apt-get -qq --yes dist-upgrade
+
+echo "Running apt-get upgrade"
+export DEBIAN_FRONTEND="noninteractive" && apt-get -qq --yes upgrade
+
+
+echo "Running apt-get purge"
+export DEBIAN_FRONTEND="noninteractive" && apt-get -qq --purge autoremove --yes
+export DEBIAN_FRONTEND="noninteractive" && apt-get -qq autoclean --yes
+