add conversation-token battery and eno1 route preference

bench-conversation.py answers 'what does this endpoint feel like': ten real
jobs streamed once, TTFT split from decode tok/s, salted so no arm inherits a
warm cache, optional concurrent burst for capacity. Needed to compare the two
tensor-parallel runtimes the 2026-09-20 board swap unblocked.

dankserver-route-primary.sh pins eno1 (the fleet address, .235) as the
preferred default route after the board swap brought up eno2 with DHCP and a
lower metric; eno2 stays up as failover. nmcli device reapply, not connection
up, so the link this session rides is not torn down.

scripts/dankserver-route-primary.sh

@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+# Pin Dankserver's fleet NIC (eno1, 192.168.0.235) as the primary default route.
+#
+# The 2026-09-20 board swap (TUF GAMING B650-E -> ProArt B850-Creator WiFi NEO)
+# brought up a second port, eno2, which took DHCP and — with NetworkManager's
+# default per-connection metric of 100 — came up with metric 101 while eno1's
+# static gateway got 102. Outbound traffic therefore started leaving by eno2
+# even though every fleet peer, Caddy upstream and monitoring target addresses
+# this host as .235. Keep eno2 (it is a real second link) but make it secondary:
+# route metrics decide the default route, so eno1 wins while eno2 stays a
+# failover.
+#
+# Run on Dankserver.  Idempotent; NetworkManager owns these connections (the
+# netplan files under /etc/netplan are its generated shim, so edit via nmcli).
+#
+#   bash scripts/dankserver-route-primary.sh [--check]
+set -euo pipefail
+
+PRIMARY='Wired connection 1'      # eno1, static 192.168.0.235, fleet address
+SECONDARY='Wired connection 2'    # eno2, DHCP 192.168.0.247
+PRIMARY_IF='eno1'
+SECONDARY_IF='eno2'
+PRIMARY_METRIC=100
+SECONDARY_METRIC=200
+
+show() {
+    printf 'routes:\n'; ip route show default
+    printf 'wanted: %s metric %s, %s metric %s\n' \
+        "$PRIMARY" "$PRIMARY_METRIC" "$SECONDARY" "$SECONDARY_METRIC"
+}
+
+if [[ "${1:-}" == '--check' ]]; then
+    for conn in "$PRIMARY" "$SECONDARY"; do
+        printf '%s: ipv4=%s ipv6=%s\n' "$conn" \
+            "$(nmcli -g ipv4.route-metric connection show "$conn")" \
+            "$(nmcli -g ipv6.route-metric connection show "$conn")"
+    done
+    show
+    exit 0
+fi
+
+nmcli connection modify "$PRIMARY" \
+    ipv4.route-metric "$PRIMARY_METRIC" ipv6.route-metric "$PRIMARY_METRIC"
+nmcli connection modify "$SECONDARY" \
+    ipv4.route-metric "$SECONDARY_METRIC" ipv6.route-metric "$SECONDARY_METRIC"
+
+# `nmcli device reapply <ifname>` pushes the edited profile without tearing the
+# link down.  `nmcli connection up` would re-run DHCP and briefly drop the route
+# this session rides on, and `connection reapply` is not a verb (NM 1.54).
+nmcli device reapply "$PRIMARY_IF"
+nmcli device reapply "$SECONDARY_IF"
+
+show
+if [[ "$(ip route show default | head -1)" != *"dev $PRIMARY_IF"* ]]; then
+    printf 'ERROR: eno1 is still not the preferred default route\n' >&2
+    exit 1
+fi
+printf 'eno1 is the preferred default route; eno2 remains up as failover.\n'