fix(jellyfin): subtitle timing, resume progress, and overlay sync

- Add per-stream subtitle delay persistence and auto timeline-offset correction
- Strip server-selected subtitle stream from mpv load URL; suppress plugin subtitle rearm and auto-start during app-managed preload
- Fix resume position lost when mpv resets on stop; use last known position for final progress/stopped reports
- Keep Play vs Resume distinct to avoid early seek race on normal play
- Fix discovery resume when remote play sends StartPositionTicks=0 despite saved progress
- Deduplicate show/hide overlay commands using recorded visibility state
- Rewrite docs-site Jellyfin page around cast-to-device UX

plugin/subminer/state.lua

@@ -42,6 +42,8 @@ function M.new()
 		pending_reload_media_identity = nil,
 		pending_reload_media_title = nil,
 		pending_reload_reason = nil,
+		app_managed_playback_pending = false,
+		app_managed_playback_active = false,
 		auto_start_retry_generation = 0,
 		session_binding_generation = 0,
 		session_binding_names = {},