Add page builder admin UI + public page route (step 5 + step 6 client)

- PagesAdmin: list view of pages (title/slug/status/protected/updated) with
  new/edit navigation and a View link to the live page.
- PageBuilder: full-page block canvas — palette (adds any registered block),
  per-block editor cards with show/hide, up/down + native drag reorder, and
  remove; Content / Settings tabs; SEO metadata + layout/nav settings panels;
  publish/unpublish; protect (PATCH) and password-gated unprotect (modal);
  draft preview (mints a token, opens /preview/:id/:token); delete (blocked
  while protected). Surfaces server block-validation details on save.
- CmsPage: public renderer for /:slug (published; staff see drafts) and the
  token-gated /preview/:id/:token, rendering blocks via BlockList and
  reflecting the page title/meta.
- Routing: /:slug catch-all after all named routes + /preview/:id/:token
  outside the maintenance gate; admin /admin/pages, /pages/new, /pages/:id.
- api client: public page/pagePreview + admin pages CRUD/unprotect/preview.
- AdminLayout: "Pages" nav entry (Content group) with icon.
- theme.css: builder canvas + preview-banner + shell-wide styles.

Client builds clean (216 modules).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/src/App.jsx

@@ -18,12 +18,15 @@ import About from './routes/public/About.jsx'
 import Status from './routes/public/Status.jsx'
 import Wiki from './routes/wiki/Wiki.jsx'
 import WikiArticle from './routes/wiki/WikiArticle.jsx'
+import CmsPage from './routes/public/CmsPage.jsx'
 
 // Admin
 import AdminLogin from './routes/admin/AdminLogin.jsx'
 import AdminLayout from './routes/admin/AdminLayout.jsx'
 import Dashboard from './routes/admin/views/Dashboard.jsx'
 import PostsAdmin from './routes/admin/views/PostsAdmin.jsx'
+import PagesAdmin from './routes/admin/views/PagesAdmin.jsx'
+import PageBuilder from './routes/admin/views/PageBuilder.jsx'
 import WikiAdmin from './routes/admin/views/WikiAdmin.jsx'
 import HeroEditor from './routes/admin/views/HeroEditor.jsx'
 import SettingsAdmin from './routes/admin/views/SettingsAdmin.jsx'
@@ -65,8 +68,15 @@ export default function App() {
             <Route path="/site/status" element={<Status />} />
             <Route path="/wiki" element={<Wiki />} />
             <Route path="/wiki/:slug" element={<WikiArticle />} />
+            {/* CMS pages: top-level /:slug, matched only after the named routes
+                above (React Router ranks static routes over this dynamic one). */}
+            <Route path="/:slug" element={<CmsPage />} />
           </Route>
 
+          {/* Draft-preview link (token-gated). Outside the maintenance gate so a
+              preview link works regardless of site mode. */}
+          <Route path="/preview/:id/:token" element={<CmsPage preview />} />
+
           {/* Admin */}
           <Route path="/admin/login" element={<AdminLogin />} />
           <Route
@@ -79,6 +89,9 @@ export default function App() {
           >
             <Route index element={<Dashboard />} />
             <Route path="posts" element={<PostsAdmin />} />
+            <Route path="pages" element={<PagesAdmin />} />
+            <Route path="pages/new" element={<PageBuilder />} />
+            <Route path="pages/:id" element={<PageBuilder />} />
             <Route path="wiki" element={<WikiAdmin />} />
             <Route path="hero" element={<HeroEditor />} />
             <Route path="settings" element={<SettingsAdmin />} />