feat(rego-tunnel): Add Dockerfile and build scripts for cisco-vpn image

Includes:
- Dockerfile for native Cisco Secure Client in Docker
- Build scripts (init-vpn.sh, startup-vnc.sh, vpn-connect.sh)
- VNC configuration (xstartup, vnc.service)
- build.sh for manual image builds
- README documenting the architecture

Note: cisco-secure-client-full.tar.gz is gitignored (large binary)
Copy it from ~/projects/cisco-vpn/build/ before building.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/rego-tunnel/build/scripts/init-vpn.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+# Cisco VPN Docker Init Script
+# Unmounts Docker's read-only bind mounts to allow VPN to modify DNS settings
+
+# Backup current DNS config
+cp /etc/resolv.conf /tmp/resolv.conf.bak 2>/dev/null || true
+cp /etc/hosts /tmp/hosts.bak 2>/dev/null || true
+
+# Unmount Docker's bind mounts (this is the key fix!)
+umount /etc/resolv.conf 2>/dev/null || true
+umount /etc/hosts 2>/dev/null || true
+
+# Restore DNS config as regular files
+cat /tmp/resolv.conf.bak > /etc/resolv.conf 2>/dev/null || echo "nameserver 8.8.8.8" > /etc/resolv.conf
+cat /tmp/hosts.bak > /etc/hosts 2>/dev/null || echo "127.0.0.1 localhost" > /etc/hosts
+
+# Start systemd
+exec /sbin/init