Tasks

Add shared Air APP lifecycle IPC contracts.
Add Launcher Air APP lifecycle service and dedicated IPC host.
Make Launcher remain alive while desktop or Air APP processes exist.
Route desktop Air APP launch requests through Launcher IPC.
Add hidden air-app-broker Launcher command for direct-host development fallback.
Make desktop fallback start air-app-broker --requester-pid <pid> instead of normal launch.
Add broker lifetime and command recognition tests.
Add AirAppHost registration and unregister best-effort calls.
Add lifecycle service and request-building tests.