chore: replace Docker Desktop references with open-source alternatives

Docker Desktop requires a commercial licence for business use. Replace all
references with free alternatives:
- macOS: Rancher Desktop (GUI) or Colima (CLI)
- Linux: Docker Engine CE (no Desktop needed at all)
- Windows: Rancher Desktop or WSL2 + Docker Engine

setup.sh detects the OS and shows platform-specific install instructions.
claude.sh defers to setup.sh for install hints to avoid duplication.
README documents all options including a WSL2 setup walkthrough.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -4,9 +4,17 @@ Runs [Claude Code](https://claude.ai/code) inside an isolated Docker environment
 
 ## Quick Start
 
-**1. Install Docker Desktop**
+**1. Install a Docker runtime**
 
-Download and install [Docker Desktop](https://www.docker.com/products/docker-desktop/) for your platform. It's free and includes everything needed — no extra tools required.
+Pick the free, open-source option for your platform:
+
+| Platform | Recommended | Alternative |
+|---|---|---|
+| macOS | [Rancher Desktop](https://rancherdesktop.io/) (GUI) | [Colima](https://github.com/abiosoft/colima) (CLI): `brew install colima docker docker-compose && colima start` |
+| Linux | Docker Engine: `curl -fsSL https://get.docker.com \| sh` | [Rancher Desktop](https://rancherdesktop.io/) |
+| Windows | [Rancher Desktop](https://rancherdesktop.io/) (GUI) | WSL2 + Docker Engine (see below) |
+
+> **Note:** Docker Desktop is not listed — it requires a commercial licence for business use.
 
 **2. Download this repo**
 
@@ -67,7 +75,13 @@ Setup will ask how you want to authenticate (API key, subscription token, or bro
 
 ## Prerequisites
 
-- [Docker Desktop](https://www.docker.com/products/docker-desktop/) (includes Docker Engine and Compose)
+A Docker runtime with Compose support. Choose a free, open-source option:
+
+- **macOS:** [Rancher Desktop](https://rancherdesktop.io/) or [Colima](https://github.com/abiosoft/colima)
+- **Linux:** [Docker Engine CE](https://docs.docker.com/engine/install/) (`curl -fsSL https://get.docker.com | sh`)
+- **Windows:** [Rancher Desktop](https://rancherdesktop.io/) or WSL2 + Docker Engine
+
+> Docker Desktop is not recommended — it requires a commercial licence for business use.
 
 ## Authentication
 
@@ -116,6 +130,16 @@ cd ~/myproject
 ./claude.sh shell         # Debug bash shell in the Claude container
 ```
 
+### Windows: WSL2 + Docker Engine (alternative to Rancher Desktop)
+
+1. Install [WSL2](https://learn.microsoft.com/en-us/windows/wsl/install): `wsl --install` in PowerShell
+2. Open the Ubuntu terminal and run:
+   ```bash
+   curl -fsSL https://get.docker.com | sh
+   sudo usermod -aG docker $USER
+   ```
+3. Log out and back in, then run `launch.bat` as usual.
+
 ### Building locally
 
 ```bash

claude.sh

@@ -17,18 +17,15 @@ error() { echo -e "${RED}[-]${NC} $*" >&2; }
 # ─── Helpers ──────────────────────────────────────────────────────────────────
 check_deps() {
     if ! command -v docker &>/dev/null; then
-        error "Docker is not installed."
+        error "Docker is not installed. Run ./setup.sh for install instructions."
-        error "  → Download Docker Desktop (free): https://www.docker.com/products/docker-desktop/"
         exit 1
     fi
     if ! docker info &>/dev/null 2>&1; then
-        error "Docker is not running."
+        error "Docker is not running. Start your Docker runtime, then try again."
-        error "  → Open Docker Desktop and wait for it to finish starting, then try again."
         exit 1
     fi
     if ! docker compose version &>/dev/null 2>&1; then
-        error "Docker Compose is not available."
+        error "Docker Compose is not available. Run ./setup.sh for install instructions."
-        error "  → Download Docker Desktop (includes Compose): https://www.docker.com/products/docker-desktop/"
         exit 1
     fi
 }

setup.sh

@@ -11,27 +11,64 @@ warn()  { echo -e "${YELLOW}[!]${NC} $*"; }
 error() { echo -e "${RED}[✗]${NC} $*" >&2; }
 step()  { echo -e "\n${BOLD}$*${NC}"; }
 
+# ─── Platform-specific install hints ─────────────────────────────────────────
+docker_install_hint() {
+    case "$(uname -s)" in
+        Darwin)
+            echo  "  Install one of the following (both are free and open source):"
+            echo  "  • Rancher Desktop (GUI, easiest): https://rancherdesktop.io/"
+            echo  "  • Colima (CLI):  brew install colima docker docker-compose && colima start"
+            ;;
+        Linux)
+            echo  "  Install Docker Engine (free, no licensing restrictions):"
+            echo  "    curl -fsSL https://get.docker.com | sh"
+            echo  "    sudo usermod -aG docker \$USER   # then log out and back in"
+            ;;
+        *)
+            # Windows / Git Bash / WSL
+            echo  "  Install one of the following (both are free and open source):"
+            echo  "  • Rancher Desktop (GUI, easiest): https://rancherdesktop.io/"
+            echo  "  • WSL2 + Docker Engine: install Ubuntu from the Microsoft Store,"
+            echo  "    then run: curl -fsSL https://get.docker.com | sh"
+            ;;
+    esac
+}
+
+docker_not_running_hint() {
+    case "$(uname -s)" in
+        Darwin|MINGW*|MSYS*|CYGWIN*)
+            echo  "  → Open Rancher Desktop (or whichever Docker runtime you installed)"
+            echo  "    and wait for it to finish starting, then run this setup again."
+            ;;
+        Linux)
+            echo  "  → Start the Docker daemon:  sudo systemctl start docker"
+            ;;
+        *)
+            echo  "  → Start your Docker runtime and try again."
+            ;;
+    esac
+}
+
 # ─── Check Docker ─────────────────────────────────────────────────────────────
 check_docker() {
     step "Checking Docker..."
 
     if ! command -v docker &>/dev/null; then
         error "Docker is not installed."
-        echo  "  → Download Docker Desktop (free): https://www.docker.com/products/docker-desktop/"
+        docker_install_hint
-        echo  "    It includes everything you need — no extra tools required."
         exit 1
     fi
 
     if ! docker info &>/dev/null 2>&1; then
         error "Docker is installed but not running."
-        echo  "  → Open Docker Desktop and wait for the whale icon to stop animating,"
+        docker_not_running_hint
-        echo  "    then run this setup again."
         exit 1
     fi
 
     if ! docker compose version &>/dev/null 2>&1; then
         error "Docker Compose is not available."
-        echo  "  → Download Docker Desktop (includes Compose): https://www.docker.com/products/docker-desktop/"
+        echo  "  Docker Compose is included with Rancher Desktop and Docker Engine."
+        docker_install_hint
         exit 1
     fi