feat(centralui): rebrand web UI to ScadaBridge + technical-light theme

Rename the user-facing product name from ScadaLink to ScadaBridge across
the six display strings (browser title, sidebar brand, login + not-authorized
headings, dashboard welcome/subtitle). Namespaces, assemblies, config keys,
and _content/ScadaLink.CentralUI asset routes are unchanged.

Apply the technical-light design system: vendor theme.css + IBM Plex fonts
into the CentralUI RCL, include theme.css globally (after Bootstrap so its
--bs-* token overrides win), and restyle the layout chrome to a light
sidebar — white surface, hairline rules, ink text, accent-blue active item,
the brand accent mark. Page markup stays Bootstrap and inherits the warm
paper background, Plex type, accent, and hairline borders via the tokens.

Tests: build 0 warnings; bUnit 542 passed; Playwright 64 passed.

src/ScadaLink.Host/Components/App.razor

@@ -4,9 +4,10 @@
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <base href="/" />
-    <title>ScadaLink</title>
+    <title>ScadaBridge</title>
     <link href="/lib/bootstrap/css/bootstrap.min.css" rel="stylesheet" />
     <link href="/lib/bootstrap-icons/bootstrap-icons.css" rel="stylesheet" />
+    <link href="_content/ScadaLink.CentralUI/css/theme.css" rel="stylesheet" />
     <link href="/ScadaLink.Host.styles.css" rel="stylesheet" />
     <link href="_content/ScadaLink.CentralUI/css/site.css" rel="stylesheet" />
     <HeadOutlet @rendermode="InteractiveServer" />