music on hold: play order set in the UI, and shuffle

Owner: the first upload always played first. A class is now an Asterisk playlist in the order
set on Sounds & music (move up/down), new uploads last, with a Shuffle option (sort = random).
moh-test.ts plays both in a real Asterisk and reads the file order from its debug log.

apps/api/src/generator/golden-case.ts

@@ -25,7 +25,7 @@ export function loadCase(name: string): Snapshot {
     timeConditions?: Partial<Snapshot['timeConditions'][number]>[];
     holidays?: Snapshot['holidays'];
     announcements?: Snapshot['announcements'];
-    mohClasses?: string[];
+    mohClasses?: { name: string; shuffle?: boolean; files: string[] }[];
   };
   const settings = Object.fromEntries(
     (Object.keys(SettingsSchemas) as SettingKey[])
@@ -117,7 +117,7 @@ export function loadCase(name: string): Snapshot {
       id: c.id!,
       number: c.number!,
     })),
-    mohClasses: raw.mohClasses ?? [],
+    mohClasses: (raw.mohClasses ?? []).map((c) => ({ shuffle: false, ...c })),
     pagingGroups: (raw.pagingGroups ?? []).map((g, i) => ({
       name: `Paging ${i + 1}`,
       duplex: false,