fix(nh3-pve): AMT reachable — hold the vPro port up; DHCP reservation + DNS

AMT had no IP because Linux had enp88s0 admin-down (it left vmbr0 on 09-25 and
had no auto stanza); igc powers off the I226-LM PHY when down, so AMT had no
link. With the port up (no IP, unbridged) AMT took a lease within minutes.

- nh3-pve: `auto enp88s0` (manual, unbridged) and sysctl.d disable_ipv6 on it;
  backup /root/interfaces.bak-20260925-amt; runtime already matched, no reload.
- UDM: reservation nh3-pve-amt -> 10.100.0.151 (untagged nh3-default; the
  cable is on an nh3-sw1 trunk, not the UDM).
- DNS nh3-pve-amt.nh3.internal. AMT 16.1.25 answers TLS :16993 and :664.

persistent-memory.md

@@ -132,11 +132,14 @@ hermes-gateway, Booth, ttyd, zellij-web and dev-backup are running.
   `servers/nh3-ml1/README.md` exists.
 - ⏳ **Prime's call: gateway routing.** Recommendation: load-share
   `qwen3-embedding` + `reranker` across esh-ml1 and nh3-ml1.
-- ⚠ **AMT is cabled (1 Gb link) and reported enabled, but not on the network.** No
-  UDM lease for `…:96:0e`, and no 16992/16993 on the four NH3 /24s (the sweep was
-  positive-controlled). It is not on the USW Pro 24, so probably nh3-sw1. Asked
-  Prime for the MEBx network settings and which switch port. **The NanoKVM stays
-  on nh3-pve until AMT KVM is confirmed.**
+- ✅ **AMT LIVE 2224: `https://10.100.0.151:16993`** (`nh3-pve-amt.nh3.internal`,
+  UDM reservation). It had no IP because Linux had the port DOWN. `igc` powers
+  off the PHY and AMT loses its link. Our own 09-25 removal of `enp88s0` from
+  vmbr0 caused that. Fix: `auto enp88s0` (up, no IP, unbridged) plus IPv6 off via
+  sysctl.d, persistent. The cable is on an **nh3-sw1 trunk** (untagged
+  nh3-default), not the UDM.
+  **Open:** check that KVM + Opt-in None are set (needs the AMT admin password),
+  then move the NanoKVM to the gx10.
 - Found and fixed: **lxc-pve 6.0.0-1 broke Docker in the CT** (runc 1.5 sysctl
   reopen denied). Upgraded that one package to 6.0.0-2 (Proxmox fix #7006), and
   `gpu-lxc.yaml` now does this itself.