Add stable keys for special groups and SSL sync agent hooks.

English keys on store/website specials stay unique per business; domain-admin can trigger dashboard SSL sync.

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

src/common/special-group-key.ts

@@ -0,0 +1,9 @@
+/** English stable key for website special group lookups (e.g. top-selling). */
+export const SPECIAL_GROUP_KEY_PATTERN = /^[a-zA-Z][a-zA-Z0-9_-]*$/;
+
+export const SPECIAL_GROUP_KEY_MESSAGE =
+  'key must be English letters, numbers, hyphens, or underscores';
+
+export function normalizeSpecialGroupKey(raw: string): string {
+  return raw.trim();
+}