feat(dr): add cluster + memory pre-flight, deploy VM 109 watchdog

DR test script now refuses to start VM 109 if:
  * cluster is not quorate (e.g. mid-failover into a degraded state),
  * available memory on the host is below VM 109 config + 1 GB margin.

Both checks scale automatically — memory threshold is computed from
qm config so resizing VM 109 does not require touching the script.

Adds vm109-watchdog.sh, scheduled cluster-wide every minute. The
watchdog is the second line of defence behind the cleanup trap from
8a0c557: it force-stops VM 109 if the trap was bypassed (script
killed, host crash mid-test, manual run forgotten). It honours
/var/run/vm109-debug.flag for legitimate manual sessions and is
node-aware via /etc/pve/qemu-server/109.conf so it can be deployed
on every node without coordinating with VM 109's current location.

Both safeguards target the 04-18 → 04-20 chain: VM 109 left running
2.5 days then sandwiched against an HA failover that pushed CT 108
Oracle (8 GB) onto pveelite (16 GB) → OOM cascade.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

proxmox/vm109-windows-dr/scripts/vm109-watchdog.sh

@@ -0,0 +1,99 @@
+#!/bin/bash
+#
+# VM 109 watchdog: stops VM 109 if running outside the DR test window.
+#
+# Why: incident 2026-04-18 — DR script crashed after starting VM 109 but
+# before stopping it. Trap was added (commit 8a0c557) but only fires on
+# script exit, not on system crash, kernel panic, or oomkill of the test
+# script itself. This watchdog is the second line of defense.
+#
+# Behavior:
+#   * If VM 109 is not running: exit silently.
+#   * If VM 109 is running and uptime <= 60 min: exit silently (test running).
+#   * If VM 109 is running, uptime > 60 min, debug flag absent, and we are
+#     OUTSIDE Saturday 05:55-07:30 EEST: alert + stop VM 109.
+#
+# Debug exemption:
+#   touch /var/run/vm109-debug.flag    # before manual debug
+#   rm    /var/run/vm109-debug.flag    # after debug
+#
+# Schedule (cron on the node hosting VM 109):
+#   * * * * * /opt/scripts/vm109-watchdog.sh
+
+set -euo pipefail
+export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+
+DR_VM_ID="109"
+DEBUG_FLAG="/var/run/vm109-debug.flag"
+LOG="/var/log/oracle-dr/watchdog.log"
+MAX_RUNTIME_S=3600   # 60 minutes outside test window
+TEST_WINDOW_START_MIN=$((5 * 60 + 55))   # Saturday 05:55
+TEST_WINDOW_END_MIN=$((7 * 60 + 30))     # Saturday 07:30
+
+mkdir -p "$(dirname "$LOG")"
+
+log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*" >>"$LOG"; }
+
+# Skip silently if VM 109 config not on this node (cluster-aware).
+[ -f /etc/pve/qemu-server/${DR_VM_ID}.conf ] || exit 0
+
+# Skip if not running
+qm status "$DR_VM_ID" 2>/dev/null | grep -q running || exit 0
+
+# Skip if debug flag set
+[ -f "$DEBUG_FLAG" ] && exit 0
+
+# Get VM 109 uptime in seconds (process etime)
+PID_FILE="/var/run/qemu-server/${DR_VM_ID}.pid"
+[ -f "$PID_FILE" ] || exit 0
+VM_PID=$(cat "$PID_FILE")
+UPTIME_S=$(ps -p "$VM_PID" -o etimes= 2>/dev/null | tr -d ' ' || echo 0)
+
+# Within first hour: assume normal test run, no action
+[ "$UPTIME_S" -le "$MAX_RUNTIME_S" ] && exit 0
+
+# Inside Saturday test window: assume manual extended test, alert but do not stop
+DOW=$(date +%u)   # 1=Mon ... 7=Sun, Saturday=6
+NOW_MIN=$(( $(date +%H) * 60 + $(date +%M) ))
+if [ "$DOW" -eq 6 ] \
+    && [ "$NOW_MIN" -ge "$TEST_WINDOW_START_MIN" ] \
+    && [ "$NOW_MIN" -le "$TEST_WINDOW_END_MIN" ]; then
+    log "VM ${DR_VM_ID} running ${UPTIME_S}s in test window — no action (alert sent)"
+    echo "VM ${DR_VM_ID} running ${UPTIME_S}s during DR test window. Investigate." \
+        | mail -s "[WARN] VM 109 long-running in test window" root 2>/dev/null || true
+    exit 0
+fi
+
+# Outside test window + uptime exceeded: alert and stop
+log "VM ${DR_VM_ID} running ${UPTIME_S}s outside test window — stopping forcefully"
+
+ZFS_REPLICA=$(zfs list -t snapshot 2>/dev/null \
+    | awk '/vm-109-disk-1@/ {print $1}' | tail -1 || echo "unknown")
+
+cat <<EOF | mail -s "[CRITICAL] VM 109 watchdog: forced stop on $(hostname)" root 2>/dev/null || true
+VM ${DR_VM_ID} (oracle-dr-windows) was running for ${UPTIME_S}s outside the
+weekly DR test window (Saturday 05:55-07:30) on $(hostname).
+
+This indicates the DR test script either crashed without invoking its
+cleanup trap, or someone started VM ${DR_VM_ID} manually without setting
+${DEBUG_FLAG}.
+
+The watchdog is force-stopping VM ${DR_VM_ID} now to prevent another
+04-20-style memory exhaustion if HA failover were to fire while VM 109
+is consuming ${DR_VM_ID} memory.
+
+Latest VM 109 ZFS replica: ${ZFS_REPLICA}
+Watchdog log: ${LOG}
+
+To run a manual test without watchdog interference:
+    touch ${DEBUG_FLAG}
+    qm start ${DR_VM_ID}
+    # ... your work ...
+    qm stop ${DR_VM_ID}
+    rm ${DEBUG_FLAG}
+EOF
+
+qm stop "$DR_VM_ID" --skiplock --timeout 60 2>>"$LOG" || \
+    log "qm stop failed for VM ${DR_VM_ID}"
+
+log "Force stop completed"