Active tab state no longer gets stuck on non-tab routes

The header navigation has a row of tabs (Pages, Stats, Banners, Project). For a long time, when you navigated to a route that was not one of those primary tabs — like /settings or /profile — one of the tabs stayed highlighted as "active". It was visually confusing because the highlighted tab did not match where you actually were.

Active state now clears properly when the current route is not a tabbed route, and the highlight only reappears when you go back to one of the main tabs.

While we were rewiring this we also added a dedicated Project menu entry for jumping into project-level settings, so the navigation feels more complete top-to-bottom.