Apply technical-light design system to the gateway dashboard

Restyles the Blazor dashboard onto a portable token-based theme so it
reads like an instrument panel: warm-paper background, hairline-ruled
panels, IBM Plex type, monospace tabular numerics, and status carried by
colour chips. Vendors theme.css + IBM Plex fonts, rewrites dashboard.css
as a thin token-driven view layer, and swaps the Bootstrap navbar and
status badges for the design-system app bar and chips.

Also includes pending API-key management, Galaxy hierarchy projection,
and constraint-enforcement work with their tests.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/MxGateway.Server/Dashboard/Components/App.razor

@@ -7,6 +7,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1" />
     <base href="@DashboardBaseHref" />
     <link rel="stylesheet" href="/lib/bootstrap/css/bootstrap.min.css" />
+    <link rel="stylesheet" href="/css/theme.css" />
     <link rel="stylesheet" href="/css/dashboard.css" />
     <HeadOutlet @rendermode="InteractiveServer" />
 </head>