feat: add notification settings with sound picker and preview

locales/en/common.json

@@ -624,7 +624,8 @@
       "files": "Files",
       "contacts": "Contacts",
       "encryption": "Encryption",
-      "sidebar_apps": "Sidebar Apps"
+      "sidebar_apps": "Sidebar Apps",
+      "notifications": "Notifications"
     },
     "tab_groups": {
       "general": "General",
@@ -696,6 +697,40 @@
       "migrating": "Updating keyword on existing emails…",
       "migration_error": "Failed to update keyword on existing emails"
     },
+    "notifications": {
+      "test_sound": "Test notification sound",
+      "sounds": {
+        "default": "Default (Beep)",
+        "cheerful": "Cheerful",
+        "involved": "Involved",
+        "swift": "Swift Gesture",
+        "relax": "Relax"
+      },
+      "sound_selection": {
+        "title": "Notification Sound",
+        "description": "Choose which sound to play for notifications",
+        "choose": "Sound",
+        "choose_desc": "Select a notification tone and click the speaker icon to preview it"
+      },
+      "email": {
+        "title": "Email Notifications",
+        "description": "Configure notifications for incoming emails",
+        "enabled": "Email notifications",
+        "enabled_desc": "Show notifications when new emails arrive",
+        "sound": "Notification sound",
+        "sound_desc": "Play an audio alert when new emails arrive"
+      },
+      "calendar": {
+        "title": "Calendar Notifications",
+        "description": "Configure notifications for calendar events",
+        "enabled": "Event notifications",
+        "enabled_desc": "Show alerts for upcoming calendar events",
+        "sound": "Notification sound",
+        "sound_desc": "Play an audio alert for calendar reminders",
+        "invitation_parsing": "Parse email invitations",
+        "invitation_parsing_desc": "Detect calendar invitations in email attachments and show calendar actions"
+      }
+    },
     "language_region": {
       "title": "Language & Region",
       "description": "Configure language and regional preferences",