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/wwwroot/css/site.css

@@ -0,0 +1,121 @@
+/* OtOpcUa Admin — view-specific layer over the technical-light theme (theme.css).
+   Tokens live in theme.css; this sheet only carries layout + the side rail. */
+
+/* ── App shell: side rail + page ─────────────────────────────────────────── */
+/* The outer flex direction is supplied by Bootstrap utilities on the wrapper
+   (`d-flex flex-column flex-lg-row`) so the mobile hamburger row stacks above
+   the rail on <lg viewports and the rail sits beside the page on lg+. */
+.app-shell {
+    align-items: stretch;
+    min-height: calc(100vh - 3.3rem);
+}
+
+.app-shell .page {
+    flex: 1;
+    min-width: 0;
+}
+
+/* ── Side rail ───────────────────────────────────────────────────────────── */
+.side-rail {
+    width: 220px;
+    flex: 0 0 220px;
+    display: flex;
+    flex-direction: column;
+    gap: 0.15rem;
+    padding: 1rem 0.7rem;
+    background: var(--card);
+    border-right: 1px solid var(--rule-strong);
+}
+
+/* On lg+ keep the side rail pinned so it stays visible when content scrolls. */
+@media (min-width: 992px) {
+    #sidebar-collapse {
+        position: sticky;
+        top: 0;
+        height: 100vh;
+        align-self: flex-start;
+        z-index: 1020;
+    }
+}
+
+/* When the side rail is collapsed under <lg viewports the Bootstrap collapse
+   container removes the fixed width; restore full width on mobile. */
+@media (max-width: 991.98px) {
+    .side-rail {
+        width: 100%;
+        min-width: 100%;
+        max-width: 100%;
+        height: auto;
+    }
+}
+
+.rail-eyebrow {
+    font-size: 0.68rem;
+    font-weight: 600;
+    text-transform: uppercase;
+    letter-spacing: 0.07em;
+    color: var(--ink-faint);
+    padding: 0.3rem 0.6rem;
+}
+
+.rail-link {
+    display: block;
+    padding: 0.4rem 0.6rem;
+    border-radius: 4px;
+    border-left: 2px solid transparent;
+    font-size: 0.86rem;
+    color: var(--ink-soft);
+}
+.rail-link:hover {
+    background: #f3f6fd;
+    color: var(--ink);
+    text-decoration: none;
+}
+.rail-link.active {
+    background: #eef2fc;
+    border-left-color: var(--accent);
+    color: var(--accent-deep);
+    font-weight: 600;
+}
+
+/* ── Session block, pinned to the rail foot ──────────────────────────────── */
+.rail-foot {
+    margin-top: auto;
+    padding-top: 0.6rem;
+    border-top: 1px solid var(--rule);
+}
+.rail-user {
+    display: block;
+    padding: 0 0.6rem;
+    font-weight: 600;
+    font-size: 0.88rem;
+}
+.rail-roles {
+    padding: 0.1rem 0.6rem 0.5rem;
+    font-family: var(--mono);
+    font-size: 0.72rem;
+    color: var(--ink-faint);
+}
+.rail-btn {
+    display: inline-block;
+    margin: 0 0.6rem;
+    padding: 0.3rem 0.7rem;
+    font-size: 0.78rem;
+    font-weight: 600;
+    color: var(--ink-soft);
+    background: var(--card);
+    border: 1px solid var(--rule-strong);
+    border-radius: 4px;
+    cursor: pointer;
+}
+.rail-btn:hover {
+    border-color: var(--accent);
+    color: var(--accent);
+    text-decoration: none;
+}
+
+/* ── Login card centring ─────────────────────────────────────────────────── */
+.login-wrap {
+    max-width: 380px;
+    margin: 3.5rem auto 0;
+}