Add WireGuard TUI implementation

- Add Go TUI with bubbletea for WireGuard management
- Implement client CRUD operations with QR code generation
- Add configuration and validation modules
- Install/update scripts for client setup
- Update Makefile to build binaries to bin/ directory
- Add .gitignore for Go projects

config.example

@@ -0,0 +1,28 @@
+# WireGuard VPN Configuration
+# Copy this file to /etc/wg-admin/config.conf and customize for your environment
+# All values are optional - script will use defaults if not set
+
+# Server domain or IP address (required for client endpoints)
+# Example: vpn.example.com or 203.0.113.10
+#SERVER_DOMAIN=vpn.example.com
+
+# WireGuard UDP port (default: 51820)
+#WG_PORT=51820
+
+# VPN IPv4 address range (default: 10.10.69.0/24)
+#VPN_IPV4_RANGE=10.10.69.0/24
+
+# VPN IPv6 address range (default: fd69:dead:beef:69::/64)
+#VPN_IPV6_RANGE=fd69:dead:beef:69::/64
+
+# WireGuard interface name (default: wg0)
+#WG_INTERFACE=wg0
+
+# DNS servers for clients (default: 8.8.8.8, 8.8.4.4)
+#DNS_SERVERS=8.8.8.8, 8.8.4.4
+
+# Log file location (default: /var/log/wireguard-admin.log)
+#LOG_FILE=/var/log/wireguard-admin.log
+
+# Minimum disk space required in MB (default: 100)
+#MIN_DISK_SPACE_MB=100