Model, registry and decision pages: next to the switch, not floating above
it. Graph page: after Export PNG (its header is built by graph.js a moment
later, so the button waits for it) instead of covering Export. Sized to
the controls beside it.
Shared, Diagrams, Registries and Decisions start closed on the model page;
folders inside keep their own default. Open or closed is still kept in
the webview state while the page is open.