fix: add unrestricted SSH key for ProxyJump on jump host

When using ProxyJump for cluster temperature monitoring, the jump host
(typically the first cluster node) needs an unrestricted SSH key to allow
connection forwarding. Previously only the restricted key with
command="sensors -j" was added, which blocked ProxyJump.

Now the setup script adds TWO keys:
1. Unrestricted key (for ProxyJump/connection forwarding)
2. Restricted key (for running sensors -j directly)

This allows containerized Pulse to:
- Connect through the jump host to other cluster nodes
- Collect temperature data from all cluster members

Fixes cluster temperature monitoring for Docker/LXC deployments.

internal/api/config_handlers.go

@@ -3865,6 +3865,16 @@ elif [ "$TEMP_MONITORING_AVAILABLE" = true ]; then
                 echo "  ✓ SSH key configured (restricted to sensors -j)"
             fi
 
+            # Add unrestricted key for ProxyJump (needed for containerized Pulse)
+            # This allows the node to act as SSH jump host to other cluster members
+            SSH_PROXYJUMP_ENTRY="$SSH_PUBLIC_KEY # pulse-proxyjump"
+            if [ -f /root/.ssh/authorized_keys ] && grep -qF "# pulse-proxyjump" /root/.ssh/authorized_keys 2>/dev/null; then
+                : # ProxyJump key already exists
+            else
+                echo "$SSH_PROXYJUMP_ENTRY" >> /root/.ssh/authorized_keys
+                chmod 600 /root/.ssh/authorized_keys
+            fi
+
             # Check if this is a Raspberry Pi
             IS_RPI=false
             if [ -f /proc/device-tree/model ] && grep -qi "raspberry pi" /proc/device-tree/model 2>/dev/null; then