AppIdProvider

Provides a unique, stable application identifier to namespace shared resources (temp files, locks, properties) and avoid conflicts when multiple apps use this library on the same machine.

Resolution order (first non-empty wins):

1. System property "compose.native.tray.appId"

2. Environment variable "COMPOSE_NATIVE_TRAY_APP_ID"

3. Main class from system property "sun.java.command" (first token)

4. Fallback to "ComposeNativeTrayApp"