Improve the Jellyfin integration setup experience and remove the need to use command-line discovery mode for normal tray-driven use. The existing --jellyfin setup popup should become a frontend for the same auth persistence path used by CLI login, with manual/recent server selection and inline feedback. The tray should expose a runtime-only Jellyfin Discovery checkbox when Jellyfin is configured so users can start or stop cast/discovery mode without changing config.
Acceptance Criteria
#1 The Jellyfin setup popup supports config/recent/default server choices, manual URL entry, username/password login, logout when a session exists, done/close, and inline success/error status without persisting passwords.
#2 CLI login and setup popup login share the same auth persistence behavior, including encrypted token storage, enabled/server/username/client metadata config patching, and recent server updates.
#3 jellyfin.recentServers is parsed, normalized, deduplicated, capped, documented, and included in generated config examples if exposed.
#4 The tray keeps Configure Jellyfin visible and shows a Jellyfin Discovery checkbox only when Jellyfin is configured with enabled integration, server URL, access token, and user ID.
#5 The tray Jellyfin Discovery checkbox starts/stops the current remote session at runtime only, announces after start, reports OSD/log status, and does not patch config.
#6 Startup auto-connect behavior remains governed by existing config, including remoteControlAutoConnect; explicit tray start can start discovery without requiring remoteControlAutoConnect.