Rename devices to <area>-<role> scheme

DC fabric: spine/leaf/border-leaf/access/host -> dc-spine, dc-leaf,
dc-border-leaf, dc-access, dc-server. Campus border leafs flipped
from border-leaf-campus to campus-border-leaf for consistency. Core,
campus spines/leafs/access/hosts unchanged.

Updates topology, annotations, all configs (hostnames + peer
descriptions), host interface files, README, TROUBLESHOOTING,
END_TO_END_TESTING, and the SVG diagram.

configs/dc-access2.cfg

@@ -0,0 +1,65 @@
+! DC-Access2 Configuration
+! L2-only access switch for VTEP2 (dc-leaf3/dc-leaf4)
+!
+hostname dc-access2
+!
+! LLDP Management0
+lldp management-address Management0
+!
+! enable gNMI API
+management api gnmi
+   transport grpc default
+   provider eos-native
+!
+! admin/admin for ssh access
+username admin privilege 15 role network-admin secret sha512 $6$xQktFrbdeqEhVzLM$.1wOJB25nw2fqYaSXDu6y4mo6AP9hngMCFe2vGDl84hWoz00Q.4unoEBqspNI0HEoRz.OZhdBHqQv12KABf0B0
+!
+! VLANs
+vlan 34
+   name vrf-gold-subnet
+!
+! Management interface
+interface Management0
+   ip address 172.16.0.42/24
+!
+! Spanning-tree
+spanning-tree mode mstp
+spanning-tree edge-port bpduguard default
+!
+! Uplink to leaf MLAG pair (Port-Channel 10)
+interface Ethernet1
+   description dc-leaf3-uplink
+   channel-group 10 mode active
+!
+interface Ethernet2
+   description dc-leaf4-uplink
+   channel-group 10 mode active
+!
+interface Port-Channel10
+   description uplink-to-leaf-mlag
+   switchport mode trunk
+   switchport trunk allowed vlan 34
+   no shutdown
+!
+! Host-facing downlink (Port-Channel 1)
+interface Ethernet3
+   description dc-server2
+   channel-group 1 mode active
+!
+interface Ethernet4
+   description dc-server2
+   channel-group 1 mode active
+!
+interface Port-Channel1
+   description dc-server2
+   switchport mode trunk
+   switchport trunk allowed vlan 34
+   port-channel lacp fallback timeout 5
+   port-channel lacp fallback individual
+   spanning-tree portfast
+   no shutdown
+!
+! Default route for management
+ip route 0.0.0.0/0 172.16.0.254
+!
+end