refactor(switches): standardize all switch names to <site>-<rack>-<function>-<NN>

Rename all 5 switches across all layers (DNS, DHCP, device hostname,
conman console, ser2net, udev symlinks, repo files) to follow the
<site>-<rack>-<function>-<count> convention:
  pfv-core-sw01    → pfv-r5-core-01     (rack 5 core)
  pfv-tor3-mgmt    → pfv-r3-tor-mgmt-01 (rack 3 mgmt TOR)
  pfv-tor3-stor    → pfv-r3-tor-stor-01 (rack 3 storage TOR)
  pfv-r2-tor-top   → pfv-r2-tor-01      (rack 2 TOR)
  subodev-torsw01  → pfv-r6-mgmt-01     (rack 6 mgmt)

Dead switch (pfv-r2-sw, port 2007) removed from mapping.txt.
pfv-rrinfra-rtr unchanged (router, not a switch).

Device hostnames changed via conman. Configs regenerated on pfv-tsys4.
All .cmds files, validate-conman.sh, and AGENTS.md updated. [#369]

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

dcinfra/console/query-remote.sh

@@ -5,7 +5,7 @@
 #
 # Usage:
 #   bash console/query-remote.sh                    # list consoles
-#   bash console/query-remote.sh pfv-core-sw01      # connect to a console
+#   bash console/query-remote.sh pfv-r5-core-01      # connect to a console
 #
 set -euo pipefail
 
@@ -52,7 +52,7 @@ if [ -z "$CONSOLE" ]; then
   conman -d "${REMOTE_HOST}:${REMOTE_PORT}" -q
   echo ""
   echo "To connect: bash $0 <console-name>"
-  echo "  e.g: bash $0 pfv-core-sw01"
+  echo "  e.g: bash $0 pfv-r5-core-01"
 else
   echo ""
   echo "--- Connecting to: $CONSOLE ---"