Revert "Refactor: rename wireguard_gateway to gateway"

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+# Ansible Role: wireguard_gateway
+
+This role configures a Linux host as a WireGuard VPN gateway,
+routing all traffic from local network clients through the VPN connection.
+
+## Role Variables
+
+- `wireguard_gateway_enabled`: Boolean flag to enable/disable gateway functionality (default: `false`)
+
+## What This Role Does
+
+When `wireguard_gateway_enabled` is `true`, the role:
+
+- Sets `net.ipv4.ip_forward=1` and `net.ipv6.conf.all.forwarding=1` in `/etc/sysctl.conf`
+- Creates custom routing table (100) to route traffic through VPN
+- Routes IPv4 and IPv6 traffic from local subnet through VPN interface
+- Allows traffic forwarding and established connections
+
+When `wireguard_gateway_enabled` is `false`, the role:
+
+- Removes all routing rules and iptables configurations
+- Disables IP forwarding in sysctl configuration
+- Cleans up custom routing tables
+
+## Example Configuration
+
+```yaml
+# In host_vars/gateway.yml
+wireguard_gateway_enabled: true
+wireguard_autostart_connection: "protonvpn-us-1"
+
+# WireGuard connection configuration
+wireguard_connections:
+  protonvpn-us-1: |
+    [Interface]
+    PrivateKey = your_private_key_here
+    Address = 10.2.0.2/32
+    DNS = 10.2.0.1
+
+    [Peer]
+    PublicKey = server_public_key
+    AllowedIPs = 0.0.0.0/0, ::/0
+    Endpoint = vpn.example.com:51820
+```
+
+## Client Configuration
+
+For client machines to route through the VPN gateway:
+
+1. **IPv4**: Set gateway to VPN gateway host's IP
+2. **IPv6**: Set IPv6 gateway to VPN gateway host's IPv6 address
+3. **Manual network config**: Disable auto-configuration to use custom gateway
+
+Example client network configuration:
+
+```yaml
+network_ipv4_address: "192.168.1.100"
+network_ipv4_gateway: "192.168.1.254"  # VPN gateway host
+network_ipv6_address: "2001:db8::100/64"
+network_ipv6_gateway: "2001:db8::254"   # VPN gateway host
+```
+
+## Technical Details
+
+### Routing Rules Created
+
+```bash
+# Policy routing rules (priority 200)
+ip rule add iif eth0 table 100 priority 200
+ip -6 rule add iif eth0 table 100 priority 200
+
+# Custom routing table (table 100)
+ip route add default dev wg-connection table 100
+ip -6 route add default dev wg-connection table 100
+```
+
+### iptables Rules Created
+
+```bash
+# IPv4 NAT masquerading
+iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -o wg-connection -j MASQUERADE
+
+# IPv4 FORWARD rules
+iptables -A FORWARD -s 192.168.1.0/24 -j ACCEPT
+iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+
+# IPv6 equivalent rules
+ip6tables -t nat -A POSTROUTING -s 2001:db8::/64 -o wg-connection -j MASQUERADE
+ip6tables -A FORWARD -s 2001:db8::/64 -j ACCEPT
+ip6tables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+```
+
+## Troubleshooting
+
+- **Check VPN connection**: `sudo wg show` should show active connection
+- **Verify routing**: `ip rule show` and `ip route show table 100`
+- **Test connectivity**: `curl ip.me` should show VPN IP from client machines
+- **Check iptables**: `sudo iptables -t nat -L -n -v` should show masquerading rules