restructure: move proxmox/ into subfolder, add pihole/ section

All existing content moved from repo root into proxmox/ to make room
for other Debian machine configs. Adds pihole/ with:

- config/pihole.toml — snapshot of current Pi-hole v6 config
- config/dnsmasq.d/99-ipxe-chainload.conf — custom PXE DHCP rules
  (EFI/BIOS iPXE chainload, fixed tag-specificity bug for UEFI boot)
- pull-config.sh <source-host> <dest-dir> — pull live config to disk
- apply-config.sh <source-dir> <dest-host> — push config to a Pi-hole

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XRzqNDrbnYR22ZgZj1Bg3s

proxmox/scripts/disable-subscription-nag.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+# Install the subscription-nag patch (lib/nag-patch.sh) as a persistent
+# standalone script under /usr/local/sbin, plus an apt Post-Invoke hook that
+# re-applies it after every dpkg run - a proxmox-widget-toolkit package
+# upgrade overwrites the patched file, so without the hook the patch would
+# silently revert on the next `apt upgrade`.
+#
+# Idempotent - safe to re-run. Run as root on the PVE host.
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=lib/common.sh
+source "${SCRIPT_DIR}/lib/common.sh"
+require_root
+
+INSTALLED="/usr/local/sbin/pve-disable-subscription-nag.sh"
+write_if_changed "$INSTALLED" "$(cat "${SCRIPT_DIR}/lib/nag-patch.sh")"
+chmod +x "$INSTALLED"
+
+HOOK="/etc/apt/apt.conf.d/85pve-nosubnag"
+write_if_changed "$HOOK" 'DPkg::Post-Invoke { "test -x /usr/local/sbin/pve-disable-subscription-nag.sh && /usr/local/sbin/pve-disable-subscription-nag.sh || true"; };'
+
+"$INSTALLED"
+echo "Subscription nag patch installed; will reapply automatically after updates."