feat: add Docker containerization for isolated execution & docs

Provide Docker Compose configuration allowing users to run Automaker
in complete isolation from their host filesystem, addressing security
concerns about AI agents having direct system access.

DISCLAIMER.md

@@ -30,6 +30,26 @@ Before running Automaker, we strongly recommend reviewing the source code yourse
 - **Virtual Machine**: Use a VM (such as VirtualBox, VMware, or Parallels) to create an isolated environment
 - **Cloud Development Environment**: Use a cloud-based development environment that provides isolation
 
+#### Running in Isolated Docker Container
+
+For maximum security, run Automaker in an isolated Docker container that **cannot access your laptop's files**:
+
+```bash
+# 1. Set your API key (bash/Linux/Mac - creates UTF-8 file)
+echo "ANTHROPIC_API_KEY=your-api-key-here" > .env
+
+# On Windows PowerShell, use instead:
+Set-Content -Path .env -Value "ANTHROPIC_API_KEY=your-api-key-here" -Encoding UTF8
+
+# 2. Build and run isolated container
+docker-compose up -d
+
+# 3. Access the UI at http://localhost:3007
+#    API at http://localhost:3008/api/health
+```
+
+The container uses only Docker-managed volumes and has no access to your host filesystem. See [docker-isolation.md](docs/docker-isolation.md) for full documentation.
+
 ### 3. Limit Access
 
 If you must run locally: