Add FreeRADIUS container for dynamic VLAN assignment

Add a FreeRADIUS server on the management network (172.16.0.200)
with test users mapped to existing VLANs (40, 34, 78) for future
802.1X/MAB dynamic VLAN assignment on access switches.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hosts/freeradius/clients.conf

@@ -0,0 +1,5 @@
+client management_network {
+    ipaddr = 172.16.0.0/24
+    secret = arista123
+    shortname = evpn-switches
+}