feat: Add GitHub Codespaces support with docker-compose-light

## Summary

Adds full GitHub Codespaces development environment configuration leveraging the new `docker-compose-light.yml` for efficient cloud development.

## Key Features

- **Lightweight Setup**: Uses `docker-compose-light.yml` which removes Redis/nginx for faster startup and lower resource usage
- **Multi-Instance Support**: Each Codespace gets isolated database volumes, perfect for testing multiple branches
- **Auto-Configuration**: Includes VS Code extensions, Python/TypeScript settings, and auto-start script
- **Developer Friendly**: Comprehensive README with SSH, VS Code, and browser connection instructions

## Implementation Details

### Files Added
- `.devcontainer/devcontainer.json` - Main configuration with:
  - Docker-in-Docker support for compose
  - Optimized VS Code extensions for Superset development
  - Smart port forwarding (9001 for frontend, 8088 for API)
  - 4-core/8GB recommended resources

- `.devcontainer/start-superset.sh` - Auto-start script that:
  - Uses unique project names per Codespace
  - Handles Docker daemon startup
  - Shows clear status and credentials

- `.devcontainer/README.md` - Developer guide covering:
  - Multiple connection methods (SSH, VS Code, browser)
  - Port forwarding instructions
  - Cost optimization tips
  - Integration with `claude --yes` workflows

## Benefits

1. **Isolated Development**: No risk to local machine when using `claude --yes`
2. **Resource Efficiency**: Laptop stays cool, Codespaces handles the load
3. **Parallel Testing**: Spin up multiple instances for different features
4. **Quick Pause/Resume**: Auto-stops when idle, resumes in ~30 seconds

## Testing

Push to fork and create a Codespace to test. The environment auto-starts Superset and forwards port 9001 with HTTPS.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

.devcontainer/devcontainer.json

@@ -0,0 +1,94 @@
+{
+  "name": "Apache Superset Development",
+  "dockerComposeFile": [
+    "../docker-compose-light.yml"
+  ],
+  "service": "superset-node-light",
+  "workspaceFolder": "/app",
+
+  // Use the light config for faster startup and lower resource usage
+  "shutdownAction": "stopCompose",
+
+  // Forward ports for development
+  "forwardPorts": [9001, 8088],
+  "portsAttributes": {
+    "9001": {
+      "label": "Superset Frontend",
+      "onAutoForward": "notify"
+    },
+    "8088": {
+      "label": "Superset Backend API",
+      "onAutoForward": "silent"
+    }
+  },
+
+  // VS Code extensions for Superset development
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-python.python",
+        "ms-python.vscode-pylance",
+        "ms-python.black-formatter",
+        "charliermarsh.ruff",
+        "dbaeumer.vscode-eslint",
+        "esbenp.prettier-vscode",
+        "ms-vscode.vscode-typescript-tslint-plugin",
+        "eamodio.gitlens",
+        "github.copilot",
+        "ms-azuretools.vscode-docker"
+      ],
+      "settings": {
+        "python.defaultInterpreterPath": "/usr/local/bin/python",
+        "python.linting.enabled": true,
+        "python.linting.pylintEnabled": false,
+        "python.formatting.provider": "black",
+        "editor.formatOnSave": true,
+        "editor.codeActionsOnSave": {
+          "source.fixAll.eslint": true
+        },
+        "[python]": {
+          "editor.defaultFormatter": "ms-python.black-formatter"
+        },
+        "[typescript]": {
+          "editor.defaultFormatter": "esbenp.prettier-vscode"
+        },
+        "[typescriptreact]": {
+          "editor.defaultFormatter": "esbenp.prettier-vscode"
+        }
+      }
+    }
+  },
+
+  // Environment variables for development
+  "remoteEnv": {
+    "FLASK_ENV": "development",
+    "SUPERSET_ENV": "development",
+    "CYPRESS_CACHE_FOLDER": "/tmp/cypress_cache",
+    // Enable hot reloading
+    "FLASK_DEBUG": "1",
+    // For multiple instances, use different project names
+    "COMPOSE_PROJECT_NAME": "${localEnv:CODESPACE_NAME}"
+  },
+
+  // Run commands after container is created
+  "postCreateCommand": "chmod +x /app/.devcontainer/start-superset.sh && echo '🚀 Superset Codespace ready! Run: .devcontainer/start-superset.sh to start'",
+
+  // Auto-start Superset on Codespace resume
+  "postStartCommand": "cd /app && .devcontainer/start-superset.sh",
+
+  // Features to add to the dev container
+  "features": {
+    "ghcr.io/devcontainers/features/docker-in-docker:2": {},
+    "ghcr.io/devcontainers/features/github-cli:1": {},
+    "ghcr.io/devcontainers/features/node:1": {
+      "version": "18"
+    }
+  },
+
+  // Memory and CPU (Codespaces will provision accordingly)
+  "hostRequirements": {
+    "cpus": 4,
+    "memory": "8gb",
+    "storage": "32gb"
+  }
+}