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/user-configuration/apply

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+# KNEL User Configuration Initializer
+# Configures user shells and other user-specific settings
+
+set -euo pipefail
+
+echo "Running user configuration initializer..."
+
+# Change shell to zsh for root
+chsh -s $(which zsh) root
+
+# Change shell to zsh for localuser if exists
+if [[ $LOCALUSER_CHECK -gt 0 ]]; then
+    chsh -s "$(which zsh)" localuser
+fi
+
+# Change shell to zsh for subodev if exists
+if [[ $SUBODEV_CHECK -gt 0 ]]; then
+    chsh -s "$(which zsh)" subodev
+fi
+
+# Enable accounting
+/usr/sbin/accton on
+
+echo "User configuration initializer completed"