Fix landing 500 from invalid Asia/Esfahan timezone.

Normalize Iran city aliases to Asia/Tehran, harden the clock, and make settings timezone a safe select.

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

packages/shared/src/index.ts

@@ -1 +1,2 @@
 export * from "./brand";
+export * from "./timezone";

packages/shared/src/timezone.ts

@@ -0,0 +1,34 @@
+const FALLBACK_TZ = "Asia/Tehran";
+
+/** Common mistaken city zones → valid IANA */
+const TZ_ALIASES: Record<string, string> = {
+  "Asia/Esfahan": FALLBACK_TZ,
+  "Asia/Isfahan": FALLBACK_TZ,
+  "Asia/Mashhad": FALLBACK_TZ,
+  "Asia/Shiraz": FALLBACK_TZ,
+  "Asia/Tabriz": FALLBACK_TZ,
+  "Iran": FALLBACK_TZ,
+};
+
+export function resolveTimezone(input?: string | null): string {
+  const raw = (input || FALLBACK_TZ).trim() || FALLBACK_TZ;
+  const candidate = TZ_ALIASES[raw] || raw;
+  try {
+    // Throws RangeError if invalid
+    Intl.DateTimeFormat("en-US", { timeZone: candidate });
+    return candidate;
+  } catch {
+    return FALLBACK_TZ;
+  }
+}
+
+export function formatClock(date: Date, timezone?: string | null, locale = "fa-IR") {
+  const tz = resolveTimezone(timezone);
+  return new Intl.DateTimeFormat(locale, {
+    timeZone: tz,
+    hour: "2-digit",
+    minute: "2-digit",
+    second: "2-digit",
+    hour12: false,
+  }).format(date);
+}