feat: add OpenCode and Crush AI coding agents to Docker image

Install both terminal-based AI coding agents alongside Happy Coder:
- OpenCode (opencode-ai/opencode) - open-source AI coding agent
- Crush (charmbracelet/crush) - OpenCode's active successor by Charm

Both are installed as Go binaries to /usr/local/bin from latest GitHub
releases and available to users via `opencode` and `crush` commands.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

CLAUDE.md

@@ -7,6 +7,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 The Dev Container is a Docker-based cloud development environment that provides:
 - Web-based GUI IDE (VSCode/Antigravity) via VNC on port 5800
 - Happy Coder AI assistant integration (manual startup)
+- OpenCode and Crush AI coding agents (terminal-based)
 - Automatic GitHub repository cloning on startup
 - Kubernetes-native deployment with persistent home storage
 - MCP (Model Context Protocol) sidecars for AI assistant integrations
@@ -68,7 +69,7 @@ Container start
 
 | File | Purpose |
 |------|---------|
-| `Dockerfile` | Image definition — installs Chrome, Node.js, VSCode, Happy Coder; creates non-root user (UID 1000) |
+| `Dockerfile` | Image definition — installs Chrome, Node.js, VSCode, Happy Coder, OpenCode, Crush; creates non-root user (UID 1000) |
 | `scripts/init-repo.sh` | Configures git credentials, clones GitHub repo |
 | `scripts/startapp.sh` | Calls init-repo.sh then opens VSCode in the workspace |
 | `chart/` | Helm chart for Kubernetes deployment |