Showing the media playback position

Implement a line-bar in the widget to indicate the current playback position. If possible, think about having a seek action from the bar.

Start by locating the taskbar widget and its existing media-control entry point, then determine how the current playback position is exposed. Verify the line-bar reflects playback progress and assess whether the bar can support seeking; completion should include a working position indicator, with seeking included only if feasible.

Written by the indexing model from the issue text.