Initial commit: Antigravity dev container with Happy Coder

Add containerized GUI development environment featuring:
- Antigravity IDE (VSCode) accessible via web browser
- Happy Coder AI assistant integration
- Automatic GitHub repository cloning on startup
- Persistent user home directory (ReadWriteMany PVC)
- Secure non-root execution as user claude (UID 1000)

Components:
- Dockerfile based on jlesage/baseimage-gui
- Startup scripts for repo initialization and app launch
- Kubernetes manifests (StatefulSet, ConfigMap, Secrets)
- Makefile for build and deployment automation
- Comprehensive documentation

Features:
- Web-based VNC interface (port 5800)
- GitHub token authentication for private repos
- Happy Coder runs as background service in workspace
- CephFS storage for persistent home directory
- Configurable display resolution and security

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>

scripts/startapp.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+# Start application script for baseimage-gui
+set -e
+
+echo "=== Starting Antigravity Dev Container ==="
+
+# Initialize repository and Happy Coder
+/usr/local/bin/init-repo
+
+# Get workspace directory
+if [ -f /tmp/workspace-dir ]; then
+    WORKSPACE_DIR=$(cat /tmp/workspace-dir)
+else
+    WORKSPACE_DIR="/workspace/default"
+fi
+
+echo "Opening Antigravity in: $WORKSPACE_DIR"
+
+# Start Antigravity (VSCode) in the workspace directory as claude user
+# The baseimage-gui will handle the GUI display
+exec sudo -u claude code --new-window --wait "$WORKSPACE_DIR"