Implement XDP firewall with real-time TUI monitoring

Features:
- High-performance packet filtering via eBPF/XDP
- Instant blocklist with dynamic CLI management
- Exact-match rules with Drop/Pass/Log actions
- CIDR-based IP range dropping via LPM trie
- Token-bucket rate limiting (IP-based and flow-based)
- Auto temp bans for rate limit violators
- Real-time event logging via BPF ring buffer
- Interactive TUI monitor with live stats

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/setup-veth.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+set -e
+
+ip link del veth0 2>/dev/null || true
+ip netns del testns 2>/dev/null || true
+
+ip link add veth0 type veth peer name veth1
+ip addr add 10.200.1.1/24 dev veth0
+ip link set veth0 up
+
+ip netns add testns
+ip link set veth1 netns testns
+ip netns exec testns ip addr add 10.200.1.2/24 dev veth1
+ip netns exec testns ip link set veth1 up
+ip netns exec testns ip link set lo up
+
+echo "veth0 (host) = 10.200.1.1"
+echo "veth1 (testns) = 10.200.1.2"