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

proxmox/perf/iperf-full-matrix.sh

@@ -288,6 +288,6 @@ echo "===== CONTEXT ====="
 echo "tsys4: USB cdc_ncm dongle (single 1G link, no bond)"
 echo "tsys5: bond0 broken (1 active slave, no LACP partner) — cable pending"
 echo "tsys6/7: working 2x1G LACP, layer3+4 hash (host side)"
-echo "Cross-rack: 4x1G LACP (pfv-r3-tor-stor → pfv-core-sw01)"
+echo "Cross-rack: 4x1G LACP (pfv-r3-tor-stor-01 → pfv-r5-core-01)"
 echo ""
 echo "All logs in: $LOG_DIR/"

proxmox/perf/scripts/conman-console.py

@@ -22,7 +22,7 @@ any network with a conman server:
 
 Usage:
     CONMAN_SERVER=console-host:7890 \\
-    python3 conman-console.py --console pfv-core-sw01 --cmds switches/pfv-core-sw01.cmds
+    python3 conman-console.py --console pfv-r5-core-01 --cmds switches/pfv-r5-core-01.cmds
 
 Lines starting with '!' or '#' in the cmds file are comments (skipped).
 Blank lines are skipped. The conman escape sequence (&.) is sent automatically
@@ -51,7 +51,7 @@ def main():
     ap = argparse.ArgumentParser(
         description="Drive a conman console session read-only via PTY")
     ap.add_argument("--console", required=True,
-                    help="console name (e.g. pfv-core-sw01)")
+                    help="console name (e.g. pfv-r5-core-01)")
     ap.add_argument("--cmds", required=True,
                     help="command file (one command per line; !/# = comment)")
     ap.add_argument("--server",