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/README.md

@@ -0,0 +1,41 @@
+# Rego Tunnel - Build Files
+
+This directory contains the Dockerfile and scripts to build the Cisco VPN Docker image.
+
+## Files
+
+- `Dockerfile` - Main Docker image definition
+- `cisco-secure-client-full.tar.gz` - Pre-extracted Cisco Secure Client installation
+- `build.sh` - Build script to create the Docker image
+- `scripts/` - Container scripts:
+  - `init-vpn.sh` - Container init (unmounts DNS files for VPN, starts systemd)
+  - `startup-vnc.sh` - VNC/noVNC startup script
+  - `vpn-connect.sh` - VPN automation script (inside container)
+  - `xstartup` - VNC session startup
+  - `vnc.service` - Systemd service for VNC
+
+## Building
+
+```bash
+cd /etc/runtipi/repos/runtipi/apps/rego-tunnel/build
+./build.sh
+```
+
+To push to registry:
+```bash
+docker push git.alexzaw.dev/alexz/cisco-vpn:latest
+```
+
+## Architecture
+
+1. **init-vpn.sh**: Unmounts Docker's bind-mounted `/etc/resolv.conf` and `/etc/hosts` (required for VPN to modify DNS), then starts systemd
+2. **systemd**: Manages vpnagentd (Cisco VPN agent) and vnc (VNC server) services
+3. **xstartup**: Runs when VNC session starts - by default launches vpnui, but can be overridden via volume mount
+4. **vpn-connect.sh**: Optional automation script for auto-login with TOTP
+
+## Runtime Mounts
+
+When running as rego-tunnel app, these are mounted:
+- `/shared` - Contains the `cisco-vpn` script with full automation
+- `/root/.vnc/xstartup` - Custom xstartup that launches terminal with cisco-vpn script
+- `/opt/scripts/init-vpn.sh` - Custom init script with network setup