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/Pages/Home.razor

@@ -0,0 +1,7 @@
+@page "/"
+
+<PageTitle>OtOpcUa</PageTitle>
+
+<h1>OtOpcUa Admin</h1>
+<p>v2 fused host. Use the nav above to manage deployments.</p>
+<p class="text-muted">Most v1 admin pages were removed by the live-edit migration — see follow-up F15 for the per-page restoration plan.</p>