Series drill-down: poster and details of the selected season or episode

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019reK4DUGYqDUjniWYJvwUW

internal/ui/configapply.go

@@ -64,3 +64,13 @@ func (a *App) restyleCovers() {
 		p.Show(p.detail, p.lastRef) // fetch the poster again for the new style
 	}
 }
+
+// forgetPane drops a detail pane that is no longer shown (a closed drill-down).
+func (a *App) forgetPane(d *detailPane) {
+	for i, p := range a.panes {
+		if p == d {
+			a.panes = append(a.panes[:i], a.panes[i+1:]...)
+			return
+		}
+	}
+}