Monitor Devin CLI with FrontierStack

Devin CLI brings Cognition's Devin coding agent to the terminal, with hand-off to Devin Cloud sessions. FrontierStack detects the devin CLI and its version on this Mac or over SSH, installs or updates it with Homebrew, and opens devin auth login. The MCP pane adds FrontierStack's credential-free bridge to Devin's user-scope ~/.config/devin/mcp_config.json, so every project gets it.