moh: music-on-hold classes, uploads, pickers for users and queues

/api/moh-classes: create (slug, not "default"), delete (409 while an
extension or queue uses it), add/play/remove files. Files are 8 kHz
wav in MOH_DIR/<class>/ and sound_files rows of kind moh. Extensions
and queues may only pick default or an existing class.

Two things found with real calls, written back into 03 and 04:
- An empty class plays silence on Asterisk 24. Only classes with
  music are rendered, so a channel asking for an empty one gets
  default.
- The generator reloads only changed files, and a file upload changes
  no config (except a class's first/last). The route sends moh reload
  after every file change.

Web: a Music on hold section on Sounds & music, and a select of sets
in the user drawer's Phone tab and the queue form. load-golden makes
the class folders like the api does. Golden case queue gains two
classes. e2e m8-t5: set made in the UI, upload listed by Asterisk, a
queue caller hears it, a user's moh_suggest, delete refused while
used, an emptied set falls back to default.

Task: M8-T5

packages/shared/src/index.ts

@@ -12,6 +12,7 @@ export * from './dids.ts';
 export * from './outbound.ts';
 export * from './voicemail.ts';
 export * from './sounds.ts';
+export * from './moh.ts';
 export * from './ringgroups.ts';
 export * from './queues.ts';
 export * from './conferences.ts';

packages/shared/src/moh.ts

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+// Music-on-hold classes (02 moh_classes, 03 §8): a named folder of music. 'default' is built in
+// (the stock opsound files) and not stored.
+import { z } from 'zod';
+import type { SoundDto } from './sounds.ts';
+
+/** Also the folder name under the MOH dir, so: a slug. */
+export const MohClassName = z
+  .string()
+  .regex(/^[a-z0-9-]{1,32}$/, 'Lowercase letters, digits and dashes')
+  .refine((n) => n !== 'default', '"default" is the built-in music');
+export const MohClassCreateSchema = z.object({ name: MohClassName });
+export type MohClassCreate = z.input<typeof MohClassCreateSchema>;
+
+export type MohClassDto = {
+  id: string;
+  name: string;
+  files: Omit<SoundDto, 'asteriskName'>[];
+  createdAt: string;
+};

packages/shared/src/sounds.ts

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later
 // Recorded prompts for IVRs, announcements and the recording notice (02 sound_files, 04 §6).
-// Music-on-hold classes and their files arrive with M8.
+// Music-on-hold files are sound_files too (kind moh), listed per class (moh.ts).
 import { z } from 'zod';
 
 export const SoundName = z.string().trim().min(1, 'Required').max(80);