Initial commit: DHCP whitelist service for direct link connections

Features:
- Docker-based DHCP server with MAC address whitelisting
- Binds to specific ethernet interface only
- NO DNS/gateway advertised (direct link only, not a router)
- Configurable network parameters (subnet, DHCP range, lease times)
- Systemd service integration for Arch/Manjaro
- Test environment with isolated network (172.20.0.0/24)
- Auto-configuration script to detect network settings
- Complete Makefile with management targets

Security:
- Only responds to whitelisted MAC addresses
- deny unknown-clients configuration
- Runs in Docker container for isolation

Configuration:
- Copy .example files to create your config
- interface.conf: Network interface to bind to
- whitelist.conf: Allowed MAC addresses
- network.conf: Network parameters (optional)

docker-compose.yml

@@ -0,0 +1,17 @@
+version: '3.8'
+
+services:
+  dhcp-server:
+    build: .
+    image: dhcp-whitelist:latest
+    container_name: dhcp-whitelist-server
+    network_mode: host
+    privileged: true
+    volumes:
+      - ./config:/config:ro
+    restart: unless-stopped
+    environment:
+      - TZ=UTC
+    cap_add:
+      - NET_ADMIN
+      - NET_RAW