feat: auto-create swap file on first boot

- Add swap creation to first-boot-containers.sh
- Size: 50% of RAM (min 2GB, max 8GB)
- Creates /swapfile, adds to /etc/fstab for persistence
- Runs before container creation to prevent OOM during startup

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/first-boot-containers.sh

@@ -37,6 +37,28 @@ wait_for_container() {
 
 log "First-boot container creation starting (host=$TARGET_IP)"
 
+# Create swap file if not present (50% of RAM, min 2GB, max 8GB)
+if ! swapon --show | grep -q /swapfile; then
+    TOTAL_MEM_KB=$(awk '/MemTotal/ {print $2}' /proc/meminfo)
+    SWAP_MB=$((TOTAL_MEM_KB / 2 / 1024))
+    [ "$SWAP_MB" -lt 2048 ] && SWAP_MB=2048
+    [ "$SWAP_MB" -gt 8192 ] && SWAP_MB=8192
+    log "Creating ${SWAP_MB}MB swap file..."
+    if dd if=/dev/zero of=/swapfile bs=1M count="$SWAP_MB" status=progress 2>>"$LOG"; then
+        chmod 600 /swapfile
+        mkswap /swapfile >>"$LOG" 2>&1
+        swapon /swapfile
+        if ! grep -q '/swapfile' /etc/fstab; then
+            echo '/swapfile none swap sw 0 0' >> /etc/fstab
+        fi
+        log "Swap created: ${SWAP_MB}MB"
+    else
+        log "WARNING: Failed to create swap file"
+    fi
+else
+    log "Swap already configured"
+fi
+
 # Ensure network exists (matches deploy)
 $DOCKER network create archy-net 2>/dev/null || true