chore(cleanup): delete OtOpcUa.Server, OtOpcUa.Admin, and obsolete v1 tests

Task 56: removes the legacy in-process Server + Admin Web project + their test
projects (Server.Tests, Admin.Tests, Admin.E2ETests). The fused OtOpcUa.Host
binary built across Phases 1-9 is now the sole production entry point.

What happened to the 47 legacy Admin Blazor pages: per follow-up F15, the
v1 architecture's draft/publish UX is replaced by v2's live-edit + snapshot-
deploy model, so a 1:1 migration is not meaningful. The mechanical move via
git mv preserves the history; service classes + page bodies that referenced
removed v1 types (ConfigGeneration, RedundancyRole, GenerationId) were
deleted. AdminUI now ships a minimal Home page + the v2 Deployments page.

Per-page rebuild against the v2 surface is tracked as F15. The v2 Deployments
page (Task 52) is the only first-party UI shipping in this PR.

Task 57: solution build green; 84+ tests green across active v2 + legacy
driver test projects.

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Layout/MainLayout.razor

@@ -0,0 +1,77 @@
+@inherits LayoutComponentBase
+
+<header class="app-bar">
+    <span class="brand"><span class="mark">&#9646;</span> OtOpcUa</span>
+    <span class="crumb">&rsaquo;</span>
+    <span class="crumb">admin console</span>
+    <span class="spacer"></span>
+    <AuthorizeView>
+        <Authorized>
+            <span class="meta">@context.User.Identity?.Name</span>
+            <span class="conn-pill" data-state="connected">
+                <span class="dot"></span><span>signed in</span>
+            </span>
+        </Authorized>
+        <NotAuthorized>
+            <span class="conn-pill" data-state="disconnected">
+                <span class="dot"></span><span>signed out</span>
+            </span>
+        </NotAuthorized>
+    </AuthorizeView>
+</header>
+
+<div class="app-shell d-flex flex-column flex-lg-row">
+    @* Hamburger toggle: visible only on viewports <lg.
+       Bootstrap collapse JS lives in bootstrap.bundle.min.js (loaded in App.razor). *@
+    <button class="btn btn-outline-secondary btn-sm d-lg-none m-2 align-self-start"
+            type="button"
+            data-bs-toggle="collapse"
+            data-bs-target="#sidebar-collapse"
+            aria-controls="sidebar-collapse"
+            aria-expanded="false"
+            aria-label="Toggle navigation">
+        &#9776;
+    </button>
+
+    <div class="collapse d-lg-block" id="sidebar-collapse">
+        <nav class="side-rail">
+            <div class="rail-eyebrow">Navigation</div>
+            <NavLink class="rail-link" href="/" Match="NavLinkMatch.All">Overview</NavLink>
+            <NavLink class="rail-link" href="/fleet" Match="NavLinkMatch.Prefix">Fleet status</NavLink>
+            <NavLink class="rail-link" href="/hosts" Match="NavLinkMatch.Prefix">Host status</NavLink>
+            <NavLink class="rail-link" href="/clusters" Match="NavLinkMatch.Prefix">Clusters</NavLink>
+            <NavLink class="rail-link" href="/reservations" Match="NavLinkMatch.Prefix">Reservations</NavLink>
+            <NavLink class="rail-link" href="/certificates" Match="NavLinkMatch.Prefix">Certificates</NavLink>
+            <NavLink class="rail-link" href="/role-grants" Match="NavLinkMatch.Prefix">Role grants</NavLink>
+            <div class="rail-eyebrow">Scripting</div>
+            <NavLink class="rail-link" href="/virtual-tags" Match="NavLinkMatch.Prefix">Virtual tags</NavLink>
+            <NavLink class="rail-link" href="/scripted-alarms" Match="NavLinkMatch.Prefix">Scripted alarms</NavLink>
+            <NavLink class="rail-link" href="/script-log" Match="NavLinkMatch.Prefix">Script log</NavLink>
+
+            <div class="rail-foot">
+                <AuthorizeView>
+                    <Authorized>
+                        <div class="rail-eyebrow">Session</div>
+                        <a class="rail-user" href="/account">@context.User.Identity?.Name</a>
+                        <div class="rail-roles">
+                            @string.Join(", ", context.User.Claims
+                                .Where(c => c.Type.EndsWith("/role")).Select(c => c.Value))
+                        </div>
+                        <form method="post" action="/auth/logout">
+                            <AntiforgeryToken />
+                            <button class="rail-btn" type="submit">Sign out</button>
+                        </form>
+                    </Authorized>
+                    <NotAuthorized>
+                        <div class="rail-eyebrow">Session</div>
+                        <a class="rail-btn" href="/login">Sign in</a>
+                    </NotAuthorized>
+                </AuthorizeView>
+            </div>
+        </nav>
+    </div>
+
+    <main class="page">
+        @Body
+    </main>
+</div>