[wlr/taskbar]: Fallback to window title for icon matching when app_id has no desktop entry

[clemenscodes]

Description:

When a window's app_id doesn't correspond to a known desktop entry, Waybar renders a fallback icon. This commonly occurs with applications running via Wine or Steam. For example, when launching games through Lutris, I often encounter multiple windows with the same app_id, such as steam_app_default or steam_app_0.

Since these windows share identical app_ids but have distinct titles, it becomes difficult to distinguish them or apply specific icons. If Waybar could optionally fall back to using the window title to search for matching desktop entries, it would enable better differentiation and customization—especially for games or Wine-based applications.

Feature Request:

Consider implementing a fallback mechanism that uses the window title to search for .desktop entries when the app_id yields no result. This would greatly enhance icon accuracy and user customization in scenarios involving Steam, Lutris, and Wine.