feat: apikey alias field + markdown/patch authorship display

- ApiKeyCreationModal: required Alias input (reuse alias = renew, with
  banner); align roles to backend allowlist (guest -> user, default
  user); fix copy bug (generatedKey.key).
- MarkdownContent + PatchCards: show author / created / last modified
  (+ by whom); formatDateTime helper (null -> "—").

Branched off fix/buildconfig-cachebust (carries the contenthash +
BuildConfig fix already deployed to prod).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/utils.js

@@ -5,3 +5,17 @@ import { twMerge } from "tailwind-merge";
 export function cn(...inputs) {
     return twMerge(clsx(inputs));
 }
+
+/** Format a backend datetime string for display; '—' when missing/invalid. */
+export function formatDateTime(value) {
+    if (!value) return "—";
+    const d = new Date(value);
+    if (isNaN(d.getTime())) return "—";
+    return d.toLocaleString(undefined, {
+        year: "numeric",
+        month: "short",
+        day: "numeric",
+        hour: "2-digit",
+        minute: "2-digit",
+    });
+}