fix(sensor-proxy): add timeouts to pmxcfs operations in installer

The container config backup and pct commands could hang indefinitely
when the Proxmox cluster filesystem (pmxcfs) is slow or unresponsive.
This caused the installer to appear to hang after printing
"Configuring socket bind mount..." with no further output.

Added timeout protection to:
- Container config backup cp operation
- pct status check
- pct config verification
- Config rollback cp operation

Related to #738

scripts/install-sensor-proxy.sh

@@ -3212,16 +3212,17 @@ if [[ "$STANDALONE" == false && "$CONTAINER_ON_THIS_NODE" == true ]]; then
     mkdir -p "$HOST_SOCKET_SOURCE"
 
     # Back up container config before modifying
+    # Use timeout since /etc/pve is a FUSE filesystem that can hang
     LXC_CONFIG_BACKUP=$(mktemp)
-    cp "$LXC_CONFIG" "$LXC_CONFIG_BACKUP" 2>/dev/null || {
-        print_warn "Could not back up container config (may not exist yet)"
+    if ! timeout 10 cp "$LXC_CONFIG" "$LXC_CONFIG_BACKUP" 2>/dev/null; then
+        print_warn "Could not back up container config (may not exist yet or pmxcfs slow)"
         LXC_CONFIG_BACKUP=""
-    }
+    fi
 
     MOUNT_UPDATED=false
     CT_RUNNING=false
     SKIP_CONTAINER_POST_STEPS=false
-    if pct status "$CTID" 2>/dev/null | grep -q "running"; then
+    if timeout 5 pct status "$CTID" 2>/dev/null | grep -q "running"; then
         CT_RUNNING=true
     fi
 
@@ -3288,11 +3289,11 @@ if [[ "$STANDALONE" == false && "$CONTAINER_ON_THIS_NODE" == true ]]; then
     fi
     rm -f "$TEMP_CONFIG"
 
-    if ! pct config "$CTID" | grep -qxF "$LOCAL_MOUNT_ENTRY"; then
+    if ! timeout 10 pct config "$CTID" 2>/dev/null | grep -qxF "$LOCAL_MOUNT_ENTRY"; then
         print_error "Failed to persist migration-safe socket mount in container config"
         if [ -n "$LXC_CONFIG_BACKUP" ] && [ -f "$LXC_CONFIG_BACKUP" ]; then
             print_warn "Rolling back container configuration changes..."
-            cp "$LXC_CONFIG_BACKUP" "$LXC_CONFIG"
+            timeout 10 cp "$LXC_CONFIG_BACKUP" "$LXC_CONFIG" 2>/dev/null || true
             rm -f "$LXC_CONFIG_BACKUP"
         fi
         exit 1