Task #389: Notification sounds + vibration with per-user customization

DB
- Added 7 user pref columns; vibration is now per-channel
  (vibrationEnabledOrder + vibrationEnabledMeeting). Defaults: ding/chime
  sounds, vibration on, mute off, volume 70.

API
- PATCH /auth/me/notification-preferences (requireAuth, whitelisted partial
  update, integer guard for volume). buildAuthUser exposes all new fields.
- OpenAPI spec updated; orval client + zod regenerated.

Frontend
- Static sound library: 8 short WAV assets under public/sounds/ + manifest
  (notification-sound-manifest.ts) mapping id -> labelKey -> URL.
- HTMLAudio-based player (notification-sounds.ts) with throttle, unlock,
  cache, and AUTOPLAY_BLOCKED_EVENT dispatch when play is denied pre-gesture.
- Settings popover: global mute, volume, slot tabs (orders/meetings) with
  per-channel sound + per-channel vibration + per-channel toggle, sound list
  with one-tap previews. Concurrency-safe optimistic updates (monotonic seq
  counter). RTL-correct toggle knob transforms.
- QuickMuteButton: one-tap topbar mute control (Volume2/VolumeX) with
  confirmation toast.
- useAudioUnlock: unlocks audio on first interaction.
- useAutoplayHint: toasts a localized "click anywhere to enable" hint when
  the player reports a blocked play attempt.
- Socket hook plays the right per-channel sound + vibration on
  notification_created (orders, executive_meeting) when the tab is hidden.
- UpcomingMeetingAlert: plays meeting reminder once per new eligible
  meeting (deduped by meetingId, survives 30s polling refetches).
- AR/EN translations added.

Pre-existing TS errors in executive-meetings.ts (font_settings) and
pre-existing test workflow failures are unrelated.

lib/api-spec/openapi.yaml

@@ -3004,7 +3004,9 @@ components:
           type: boolean
         notifyMeetingsEnabled:
           type: boolean
-        vibrationEnabled:
+        vibrationEnabledOrder:
+          type: boolean
+        vibrationEnabledMeeting:
           type: boolean
         notificationsMuted:
           type: boolean
@@ -3055,7 +3057,9 @@ components:
           type: boolean
         notifyMeetingsEnabled:
           type: boolean
-        vibrationEnabled:
+        vibrationEnabledOrder:
+          type: boolean
+        vibrationEnabledMeeting:
           type: boolean
         notificationsMuted:
           type: boolean
@@ -3082,7 +3086,8 @@ components:
         - notificationSoundMeeting
         - notifyOrdersEnabled
         - notifyMeetingsEnabled
-        - vibrationEnabled
+        - vibrationEnabledOrder
+        - vibrationEnabledMeeting
         - notificationsMuted
         - notificationVolume
         - roles