feat: Add Docker and SSH sandbox backend support

[Peefy]

Summary

Expand the sandbox execution system to support Docker containers and SSH remote execution as additional isolation backends beyond the existing Native, Claude (srt), and Vercel providers.

Motivation

OpenLoomi currently has a well-architected sandbox system (packages/ai/src/agent/sandbox/) with:

• NativeProvider — direct host execution (no isolation)
• ClaudeProvider — process isolation via Anthropic srt
• VercelProvider — VM isolation via Firecracker MicroVMs

However, it's missing two common enterprise-grade isolation options:

Backend	Use Case	Priority
Docker	Container isolation, reproducible environments	High
SSH	Remote server execution, CI/CD integration	Medium

Current Sandbox Architecture

packages/ai/src/agent/sandbox/
├── types.ts           # ISandboxProvider interface
├── plugin.ts          # BaseSandboxProvider, defineSandboxPlugin()
├── registry.ts        # SandboxRegistry
└── providers/
    ├── native.ts      # ✅ existing
    ├── claude.ts      # ✅ existing
    ├── vercel.ts      # ✅ existing
    ├── docker.ts      # ❌ missing
    └── ssh.ts         # ❌ missing

Implementation Details

Docker Backend

• Use Docker Engine API or docker CLI
• Support image specification (node, python, bun)
• Resource limits (CPU, memory, network)
• Volume mounts for workspace
• Container lifecycle management

interface DockerConfig {
  image: string;           // e.g., \"node:22\", \"python:3.13\"
  network: 'bridge' | 'none';
  memory?: string;         // e.g., \"512m\"
  cpu?: number;            // e.g., 1
  volumes?: string[];      // mount points
}

SSH Backend

• Use ssh2 library or CLI
• Support key-based and password authentication
• Command execution with timeout
• Stream output back to client
• Connection pooling

interface SSHConfig {
  host: string;
  port: number;
  username: string;
  auth: 'key' | 'password';
  privateKey?: string;
  password?: string;
  cwd?: string;            // working directory
  timeout?: number;
}

Requirements

• Follow existing ISandboxProvider interface
• Implement exec() and runScript() methods
• Add provider to BuiltinSandboxProviderType
• Schema validation via getDockerConfigSchema(), getSSHConfigSchema()
• Register in SandboxRegistry
• Unit tests
• Documentation

References

• Docker Engine API: https://docs.docker.com/engine/api/
• ssh2 library: https://www.npmjs.com/package/ssh2