v0.4.0 - AvailableCommands & Models Support

What's New

Features

• AvailableCommandsUpdate: Now sends available slash commands to ACP clients after session creation
• SessionModelState: Returns available models (default/Opus, Sonnet, Haiku) in NewSessionResponse

Technical Details

• Uses get_server_info() from Claude SDK to fetch commands and models
• Filters unsupported commands (cost, login, logout, etc.)
• Handles MCP commands with proper naming convention

This brings feature parity with the TypeScript implementation for model and command discovery.