Add UPS battery replacement procedure and maintenance shutdown script

Adds complete procedure for replacing UPS battery when entire cluster
is powered by the same UPS, requiring full cluster shutdown.

New files:
- scripts/ups-maintenance-shutdown.sh: Automated orchestrated shutdown
  for maintenance operations with confirmation prompts and progress display
- docs/UPS-BATTERY-REPLACEMENT.md: Complete step-by-step guide for battery
  replacement including pre-shutdown, physical replacement, and post-startup
  verification procedures

Features:
- Orchestrated shutdown: VMs → LXC containers → secondary nodes → primary
- Interactive confirmation before shutdown
- Color-coded progress indicators
- Countdown timers for each phase
- Post-replacement verification checklist
- Troubleshooting guide for common issues
- Recovery procedures for cluster/quorum problems

The procedure accounts for all 3 cluster nodes (pve1, pvemini, pveelite)
being on the same UPS, requiring complete infrastructure shutdown.

Documentation includes:
- When to replace battery (based on monthly test results)
- Pre-planning and user notification templates
- Physical battery replacement safety procedures
- Cluster recovery and VM restart procedures
- Post-replacement testing and verification
- 24-hour and 1-week monitoring checklists

Estimated maintenance window: 30-60 minutes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

proxmox/ups/README.md

@@ -19,12 +19,14 @@ proxmox/ups/
 │   ├── ups-shutdown-cluster.sh         # Script principal shutdown orchestrat
 │   ├── ups-shutdown-test.sh            # Script test (dry-run)
 │   ├── upssched-cmd                    # Handler evenimente upssched
-│   └── ups-monthly-test.sh             # Test lunar automat baterie (NOU!)
+│   ├── ups-monthly-test.sh             # Test lunar automat baterie
+│   └── ups-maintenance-shutdown.sh     # Shutdown pentru mentenanță UPS (NOU!)
 └── docs/                               # Documentație
     ├── INSTALARE-NUT.md                # Ghid instalare NUT pe Proxmox
     ├── INSTALARE-WINNUT.md             # Ghid instalare WinNUT pe Windows
     ├── UPS-SHUTDOWN-README.md          # Documentație completă sistem
-    └── UPS-MONTHLY-TEST.md             # Documentație test lunar baterie (NOU!)
+    ├── UPS-MONTHLY-TEST.md             # Documentație test lunar baterie
+    └── UPS-BATTERY-REPLACEMENT.md      # Procedură înlocuire baterie (NOU!)
 ```
 
 🎯 Utilizare:
@@ -399,6 +401,12 @@ iptables -A INPUT -p tcp --dport 3493 -s 10.0.20.0/24 -j ACCEPT
 - NUT server pe pvemini expune date la toate nodurile
 - Logging complet evenimente și teste
 
+### ✅ Mentenanță Baterie (NOU!)
+- Script automat shutdown orchestrat pentru înlocuire baterie
+- Procedură pas-cu-pas completă cu checklist-uri
+- Recovery procedures pentru probleme comune
+- Documentație: [`docs/UPS-BATTERY-REPLACEMENT.md`](docs/UPS-BATTERY-REPLACEMENT.md)
+
 ## Autori și Istoric
 
 - **Creat:** 2025-10-06