Add PBS helper script for backup monitoring

~/bin/pbs provides:
- status: Overview with datastore, storage, dedup ratio, task summary
- tasks: Recent backup/prune tasks with timestamps
- errors: Filter for failures only
- gc: Garbage collection details
- snapshots: List recent backups per namespace
- storage: Detailed dedup statistics

Also installed bc for calculations.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -78,6 +78,18 @@ The `~/bin/dns` script manages Technitium DNS (internal zone: lab.georgsen.dk):
 ~/bin/dns lookup <name>            # Query DNS
 ```
 
+## PBS (Proxmox Backup Server) Access
+
+The `~/bin/pbs` script shows backup status and statistics:
+```bash
+~/bin/pbs status          # Overview: datastores, storage, dedup, tasks
+~/bin/pbs tasks [hours]   # Show recent tasks (default: 24h)
+~/bin/pbs errors [hours]  # Show only failures (default: 72h)
+~/bin/pbs gc              # Garbage collection status
+~/bin/pbs snapshots [ns]  # List recent snapshots
+~/bin/pbs storage         # Detailed storage/dedup stats
+```
+
 ## Beszel Dashboard Access
 
 The `~/bin/beszel` script manages the server monitoring dashboard:

README.md

@@ -39,6 +39,7 @@ Helper scripts available:
 - `~/bin/dns` - Technitium DNS API
 - `~/bin/kuma` - Uptime Kuma monitoring API
 - `~/bin/beszel` - Beszel server dashboard API
+- `~/bin/pbs` - PBS backup status and statistics
 
 ## Quick Links