agent-desktop now speaks MCP

This is a meaningful interoperability upgrade: agent-desktop moves from a useful CLI to a drop-in computer-use backend for MCP-native agents.

• –One MCP configuration exposes commands such as snapshots, clicks, typing, window management, notifications, and clipboard control.
• –Stdin support keeps sensitive text out of shell arguments and reduces accidental exposure in process listings or logs.
• –Accessibility-tree automation is more structured and verifiable than screenshot-based clicking, though apps still need usable accessibility metadata.
• –The macOS row-selection fix targets awkward native interfaces such as Spotlight, where the selectable target is the list row rather than an obvious child control.
• –Because agent-desktop supplies control primitives rather than a model, developers can pair it with their preferred MCP-compatible agent and model.