CLI mode: read-only JSON device list (R1)

[janthoXO]

Future work, DESIGN.md sections 7.1 and 7.4 (decision R1).

The same binary runs in CLI mode when it gets arguments (for example KlangLadder list output).

Behavior

• Read devices and the current default from Core Audio.
• Read config.json.
• Compute ranks and status (active, connected, disconnected, disabled).
• Print JSON and exit.
• Never write the config. Never switch devices. Never start the menu bar UI.
• Reuse KlangLadderCore, so there is no second ranking implementation.
• Read older and newer config versions it understands; report an error otherwise (section 10).

Needed by: the Raycast "Switch Device" and "Manage Priorities" commands.

Note: R1 needs an unsandboxed build. A sandboxed App Store build would use AppleScript (R2) instead.