feat(backend): add SaluteSpeech to task dispatch (ENGINE_MAP + elif branch)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cpv3/modules/tasks/schemas.py

@@ -83,7 +83,7 @@ class TranscriptionGenerateRequest(Schema):
 
     file_key: str = Field(..., description="Storage key of the input file")
     project_id: UUID | None = Field(default=None, description="Associated project ID")
-    engine: Literal["whisper", "google"] = Field(
+    engine: Literal["whisper", "google", "salutespeech"] = Field(
         default="whisper", description="Transcription engine to use"
     )
     language: str | None = Field(default=None, description="Language code (e.g., 'en')")
@@ -164,5 +164,5 @@ class TaskWebhookEvent(Schema):
             )
         )
         if not has_update:
-            raise ValueError("Webhook event must include at least one update field.")
+            raise ValueError("Событие вебхука должно содержать хотя бы одно обновляемое поле.")
         return self