feat: add privacy, terms, and cookies pages

Footer and login legal links were stubs. Point them at real marketing
pages that follow the Figma content-page template.

app/(marketing)/privacy/page.tsx

@@ -0,0 +1,27 @@
+/**
+ * Figma: "Content page Template" (19003:23305)
+ * https://www.figma.com/design/agv0VBLiBlcnSAaiAORgPR/Community-Rule-System?node-id=19003-23305
+ */
+import type { Metadata } from "next";
+import messages from "../../../messages/en/index";
+import { legalPathForSlug } from "../../../lib/legalSyntheticPost";
+import LegalDocumentPage, {
+  legalPageMetadata,
+} from "../_components/LegalDocumentPage";
+
+const SLUG = "privacy" as const;
+const PATH = legalPathForSlug(SLUG);
+
+export function generateMetadata(): Metadata {
+  return legalPageMetadata(messages.metadata.privacy, messages.pages.privacy);
+}
+
+export default function PrivacyPage() {
+  return (
+    <LegalDocumentPage
+      slug={SLUG}
+      path={PATH}
+      page={messages.pages.privacy}
+    />
+  );
+}