New Hive dashboard layout with sidebar and logo

The dashboard now renders inside a shared Hive shell: a header bar with the Hive logo, a sidebar for Projects, Domains, Forage, Specs, Drops, and Audit, and a content area for each page. The previous overview page was replaced with a simpler title and Getting started card. The new shell is produced by a Layouts.dashboard component so individual pages render only their content into a slot. This change ships the Hive honeycomb logo as the headerbar, login frame, and favicon asset.