fix: managed playback overlay lifecycle for launcher-owned sessions

- Remove --background from launcher-owned mpv starts; quit only non-tray/non-background managed sessions
- Defer autoplay-ready signal until overlay window content is loaded; retry after flush
- Retry socket availability before auto-starting overlay (up to 25 attempts, 200ms apart)
- Extract warm tokenization signal into autoplay-tokenization-warm-release with stale-media guard
- Queue second-instance commands until app ready runtime completes
- Guard globalShortcut cleanup with isAppReady check to avoid pre-ready crash
- Recognize "osx" as a macOS platform alias in Lua environment detection

plugin/subminer/state.lua

@@ -37,6 +37,7 @@ function M.new()
 		force_ready_overlay_restore = false,
 		current_media_identity = nil,
 		pending_reload_media_identity = nil,
+		auto_start_retry_generation = 0,
 		session_binding_generation = 0,
 		session_binding_names = {},
 		session_numeric_binding_names = {},