Add nftables support with config generator and IP checker (#22)

* Add nftables support with config generator and IP checker

- Add generate_nft_blacklist.py for generating nftables configurations
- Add check_nft_blacklist.py for verifying IPs against blacklist
- Add blacklists_updater_nftables.sh for automated updates
- Add blacklists_nftables/ directory with generated configs
- Add GitHub Actions workflow for daily nftables updates
- Update README.md with nftables usage instructions

nftables is a modern replacement for iptables with better performance
and lower memory usage, especially for large rulesets. This addition
complements the existing iptables and nginx blacklist formats.

* Added nftables scripts help

blacklists_updater_nftables.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+# Generates nftables blacklist configurations from the main blacklist
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+INPUT_FILE="$SCRIPT_DIR/blacklists/blacklist.txt"
+OUTPUT_DIR="$SCRIPT_DIR/blacklists_nftables"
+
+# Create output directory if it doesn't exist
+mkdir -p "$OUTPUT_DIR"
+
+echo "Generating nftables blacklists..."
+
+# Generate mixed IPv4/IPv6 blacklist
+python3 "$SCRIPT_DIR/generate_nft_blacklist.py" \
+    "$INPUT_FILE" \
+    "$OUTPUT_DIR/blacklist.nft"
+
+# Generate IPv4-only blacklist
+grep -E '^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+' "$INPUT_FILE" > /tmp/blacklist-v4.txt || true
+python3 "$SCRIPT_DIR/generate_nft_blacklist.py" \
+    /tmp/blacklist-v4.txt \
+    "$OUTPUT_DIR/blacklist-v4.nft"
+
+# Generate IPv6-only blacklist
+grep -E '^[0-9a-fA-F:]+:' "$INPUT_FILE" > /tmp/blacklist-v6.txt || true
+python3 "$SCRIPT_DIR/generate_nft_blacklist.py" \
+    /tmp/blacklist-v6.txt \
+    "$OUTPUT_DIR/blacklist-v6.nft"
+
+# Clean up temp files
+rm -f /tmp/blacklist-v4.txt /tmp/blacklist-v6.txt
+
+echo "nftables blacklists generated successfully!"