feat(desktop): implement phase 2 native capabilities

backend/app/schemas/notification.py

@@ -16,5 +16,33 @@ class NotificationItem(BaseModel):
     change_summary: str | None = None
     effective_at: datetime | None = None
     created_at: datetime
+    study_id: uuid.UUID | None = None
+    study_name: str | None = None
+    delivered_at: datetime | None = None
+    read_at: datetime | None = None
 
     model_config = ConfigDict(from_attributes=True)
+
+
+class DesktopNotificationSubscriptionRead(BaseModel):
+    enabled: bool
+    enabled_at: datetime | None = None
+
+
+class DesktopNotificationSubscriptionUpdate(BaseModel):
+    enabled: bool
+
+
+class DesktopNotificationClaimRequest(BaseModel):
+    limit: int = 20
+
+
+class DesktopNotificationClaimResponse(BaseModel):
+    claim_token: uuid.UUID | None = None
+    lease_expires_at: datetime | None = None
+    items: list[NotificationItem]
+
+
+class DesktopNotificationAckRequest(BaseModel):
+    claim_token: uuid.UUID
+    delivered_ids: list[uuid.UUID]