feat: add SEO metadata, llms.txt, and markdown page mirrors

Centralize site metadata and social URLs for JSON-LD, expose llmstxt.org
content and per-page .md routes for LLM crawlers, and refactor blog/FAQ/events
pages with shared components.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/lib/meetupEventTime.ts

@@ -52,6 +52,27 @@ export function getMeetupStartUtc(dateStr: string, timeStr: string): Date {
   return new Date(Date.UTC(year, month - 1, day, utcStartH, startM, 0));
 }
 
+/**
+ * Returns the event end instant in UTC when the time string carries a range
+ * (e.g. "18:00 - 21:00"), otherwise null. Used for schema.org Event.endDate.
+ */
+export function getMeetupEndUtc(dateStr: string, timeStr: string): Date | null {
+  const key = normalizeMeetupDateKey(dateStr);
+  if (!key) return null;
+  const parts = key.split("-").map(Number);
+  const year = parts[0];
+  const month = parts[1];
+  const day = parts[2];
+  if (!year || !month || !day) return null;
+
+  const timeParts = (timeStr?.trim() || "").split(/\s*[-–]\s*/);
+  if (timeParts.length < 2 || !timeParts[1]?.trim()) return null;
+
+  const { h: endH, m: endM } = parseLocalTime(timeParts[1]);
+  const utcEndH = endH - BRUSSELS_OFFSET_HOURS;
+  return new Date(Date.UTC(year, month - 1, day, utcEndH, endM, 0));
+}
+
 const UTC_CAL_OPTS = { timeZone: "UTC" } as const;
 
 /**