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/switch-to-no-subscription-repo.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+# Remove the Proxmox/Ceph enterprise apt sources (which fail on apt update
+# without a paid subscription) and switch to the no-subscription repo.
+# Handles both the legacy one-line .list format and the deb822 .sources
+# format current PVE installers write.
+# 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
+
+SOURCES_DIR="/etc/apt/sources.list.d"
+
+# Any sources file pointing at the enterprise host gets moved out of apt's
+# way entirely (renamed .disabled) rather than commented out in place -
+# apt only reads *.sources/*.list, so this fully removes it from
+# consideration while keeping a copy on disk for reference.
+for f in "${SOURCES_DIR}"/*.sources "${SOURCES_DIR}"/*.list; do
+    [ -f "$f" ] || continue
+    grep -qi 'enterprise.proxmox.com' "$f" 2>/dev/null || continue
+    mv "$f" "${f}.disabled"
+    echo "Removed enterprise source (renamed to .disabled): $f"
+done
+
+write_if_changed "${SOURCES_DIR}/pve-no-subscription.sources" "Types: deb
+URIs: http://download.proxmox.com/debian/pve
+Suites: $(pve_codename)
+Components: pve-no-subscription
+Signed-By: /usr/share/keyrings/proxmox-archive-keyring.gpg"
+
+# Clean up a legacy-format no-subscription file from a previous run of an
+# older version of this script, to avoid two sources for the same repo.
+LEGACY_NOSUB="${SOURCES_DIR}/pve-no-subscription.list"
+if [ -f "$LEGACY_NOSUB" ]; then
+    rm -f "$LEGACY_NOSUB"
+    echo "Removed superseded $LEGACY_NOSUB"
+fi
+
+apt-get update
+echo "Repo switched. Review 'apt list --upgradable' before upgrading."