Add complete UPS monitoring system with monthly battery testing

This commit adds a comprehensive UPS monitoring and management system for
the Proxmox cluster with automated shutdown orchestration and monthly
battery health testing.

Features:
- NUT (Network UPS Tools) configuration for INNO TECH USB UPS
- Automated cluster shutdown on power failure (3-minute grace period)
- Monthly automated battery testing with health evaluation
- Email notifications via PVE::Notify system
- WinNUT monitoring client for Windows VM 201

Components added:
- config/: NUT configuration files (ups.conf, upsd.conf, upsmon.conf, etc.)
- scripts/ups-shutdown-cluster.sh: Orchestrated cluster shutdown
- scripts/ups-monthly-test.sh: Monthly battery test with email reports
- scripts/upssched-cmd: Event handler for UPS state changes
- docs/: Complete installation and usage documentation

Key findings:
- UPS battery.charge reporting has 10-40 second delay after test start
- Test must monitor voltage drop (1.5-2V) and charge drop (9-27%)
- Battery health evaluation: EXCELLENT/GOOD/FAIR/POOR based on discharge rate
- Email notifications use Handlebars templates without Unicode emojis for compatibility

Configuration:
- UPS: INNO TECH (Voltronic protocol, vendor 0665:5161)
- Primary node: pvemini (10.0.20.201) with USB connection
- Monthly test: cron 0 0 1 * * /opt/scripts/ups-monthly-test.sh
- Shutdown timer: 180 seconds on battery before cluster shutdown

Documentation includes complete installation guides for NUT server,
WinNUT client, and troubleshooting procedures.

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

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

proxmox/ups/config/ups.conf

@@ -0,0 +1,7 @@
+[nutdev1]
+    driver = nutdrv_qx
+    port = auto
+    vendorid = 0665
+    productid = 5161
+    subdriver = cypress
+    desc = "UPS Cypress via USB"