Fix window chrome positioning on Sway

Improves focused-window geometry so chrome placement stays stable across workspaces and floating containers. WindowService now exposes focused workspace X/Y, resolves workspace by name, and publishes those offsets with focused geometry. The Sway backend now tracks the active floating frame through recursion and consistently derives frame/deco/content rects from that frame. QML chrome placement was updated to use workspace-relative coordinates and simpler direct margins (removing interpolation behaviors), with safer title-bar height handling for vertical centering.

core/windows/WorkspaceModel.hpp

@@ -35,6 +35,7 @@ public:
     void setWorkspaces(QVector<WorkspaceInfo> workspaces);
     const WorkspaceInfo *workspaceAt(int row) const;
     const WorkspaceInfo *focusedWorkspace() const;
+    const WorkspaceInfo *workspaceByName(const QString &name) const;
 
 signals:
     void countChanged();