[eagleoflqj]

Replaces the simulator-ready placeholder with target selection from the sidebar and toolbar, showing the device name, runtime, state, and copyable UDID. Shutdown devices can be started with simctl bootstatus -b; confirmed startup opens Device Hub or Simulator. Refreshes preserve the selected device, and independent startup operations keep their own progress and diagnostics.

Uses a native sidebar list for keyboard navigation and scrolling, a flat device menu with a selection checkmark, and stable icon, title, and button sizing. Preserves the empty-state toolbar spacing and includes English and Simplified Chinese translations.

Centralizes process execution in Command.run, Command.xcrun, and Command.simctl. Discovery, startup, and Debug previews share the wrappers while retaining command injection and the existing background execution and cancellation behavior.

Validation:

• Release and Debug builds passed, along with all 9 Release tests and the Debug preview test.
• Native UI checks at 900×600 covered English and Simplified Chinese menus, empty states, startup progress, and layout stability.
• Actual keyboard events traversed 40 devices, revealed offscreen selections fully, and verified Tab and Shift-Tab entry and exit.
• Startup commands, errors, cancellation, concurrent starts, and overlapping refreshes were tested with injected backends. A real simulator boot was not tested locally because no simulator runtime is installed.