Add VM host deployment scripts (cloud-init + post-install)

Recommended base: Debian 13 Trixie (matches opencode-devbox base image).
- cloud-init.yml: automated VM provisioning for Proxmox/OpenStack/cloud providers
- setup-host.sh: interactive post-install script for manually-created VMs
- README.md: documents both paths and VM sizing recommendations

Installs Docker (official repo), Compose v2, ufw firewall, mosh support,
and the IPv4 DNS preference workaround for Docker Hub IPv6 issues.

deploy/README.md

@@ -0,0 +1,70 @@
+# Deploy — Host VM setup
+
+Scripts for setting up a fresh Linux VM to host opencode-devbox.
+
+## Files
+
+- **`cloud-init.yml`** — cloud-init user-data template for automated VM provisioning on OpenStack, Proxmox, or any cloud with cloud-init support
+- **`setup-host.sh`** — interactive post-install script for VMs that weren't provisioned with cloud-init
+
+## Supported distributions
+
+- **Debian 13 (Trixie)** — recommended (matches opencode-devbox base image)
+- **Ubuntu 24.04 LTS** — also works
+
+Other distributions will need manual adaptation.
+
+## Quick start
+
+### Option 1: Cloud-init (automated)
+
+Customize `cloud-init.yml` — replace the SSH public key and optionally the hostname/timezone. Then use it during VM creation:
+
+- **Proxmox**: attach as cloud-init user-data
+- **OpenStack**: `openstack server create --user-data cloud-init.yml ...`
+- **AWS/DigitalOcean/etc**: paste into the "user data" field
+
+The VM boots with Docker installed, firewall configured, and your SSH key authorized. Log in as the `devbox` user.
+
+### Option 2: Post-install script (manual)
+
+On a fresh Debian/Ubuntu VM:
+
+```bash
+curl -fsSL https://gitea.jordbo.se/joakimp/opencode-devbox/raw/branch/main/deploy/setup-host.sh | bash
+```
+
+Or clone and run:
+
+```bash
+git clone https://gitea.jordbo.se/joakimp/opencode-devbox
+cd opencode-devbox/deploy
+./setup-host.sh
+```
+
+## What gets installed
+
+- Docker Engine (from Docker's official apt repo, not distro's `docker.io`)
+- Docker Compose plugin (v2)
+- `tmux`, `mosh`, `git`
+- `ufw` firewall with SSH (22) and mosh (UDP 60000-61000) allowed
+- IPv4 DNS preference (works around Docker Hub IPv6 connectivity issues)
+
+## VM sizing recommendations
+
+| Use case | vCPU | RAM | Disk |
+|---|---|---|---|
+| Minimum | 2 | 4 GB | 20 GB |
+| Recommended | 4 | 8 GB | 40 GB |
+| Heavy use (Rust/Python builds, multi-project) | 8 | 16 GB | 80 GB |
+
+## After VM setup
+
+```bash
+mkdir -p ~/opencode-devbox && cd ~/opencode-devbox
+curl -sL https://gitea.jordbo.se/joakimp/opencode-devbox/raw/branch/main/docker-compose.yml -o docker-compose.yml
+curl -sL https://gitea.jordbo.se/joakimp/opencode-devbox/raw/branch/main/.env.example -o .env
+vim .env                                           # configure provider and keys
+docker compose up -d
+docker compose exec -u developer devbox opencode
+```