Folder Write Approvals, Non-Interactive Cloud Sessions, and Workflow Plan Previews

This release lets you allow a whole folder when a V3 session asks to write a file. V3 cloud sessions now run from non-interactive commands, and a workflow shows its plan before any step runs. It also adds three V3 output styles and gives selected workflow steps access to Powers and MCP servers. Fixes cover non-interactive runs, model fallback, MCP sign-in, and workflows.