Show the running version on Settings > General

The General page ends with a Version block naming the release this
server runs, so an update can be confirmed from the app.

The version is COBBLE_VERSION, the release tag the image was built with
(Dockerfile ARG, passed by the release workflow, which falls back to
package.json's version on a workflow-dispatch build), else package.json's
version, which a development server reports too, with (development)
after it. runningVersion (src/utils/running-version.ts) drops an
unusable version string rather than showing it.

Also includes the working tree's pending signup guard in
src/pages/__root.server.ts: a user who still holds a session while the
install has no users is sent to /auth/logout (and may load it).

src/pages/admin/settings/general/index.tsx

@@ -1,6 +1,7 @@
 import AppearanceSection from "./(sections)/appearance-section";
 import PromptSection from "./(sections)/prompt-section";
 import StorageSection from "./(sections)/storage-section";
+import VersionSection from "./(sections)/version-section";
 import SettingsShell from "../(partials)/settings-shell";
 import settingsPageMeta from "../(functions)/settings-page-meta";
 
@@ -13,6 +14,7 @@ export default function AdminSettingsGeneralPage() {
             <AppearanceSection />
             <PromptSection />
             <StorageSection />
+            <VersionSection />
         </SettingsShell>
     );
 }