multiview 复用统一的 task_id 校验

删除 submit_multiview_to_model 中重复的空白判断，改为调用 common::validate_task_id

task_id 非法时的错误字段由 Inputs 改为更精确的 TaskId，与 get_task、download_model 保持一致

server-rs/crates/platform-tripo/src/multiview_to_model/client.rs

@@ -9,7 +9,7 @@ use tripo3d_sdk::{models::FileInput, params::MultiviewToModelParams};
 
 use crate::common::{
     TripoError, TripoField, TripoGenerationOptions, TripoProviderClient, TripoTaskHandle,
-    TripoValidationReason, validate_generation_options,
+    TripoValidationReason, validate_generation_options, validate_task_id,
 };
 
 impl TripoProviderClient {
@@ -48,14 +48,7 @@ impl TripoProviderClient {
                     });
                 }
             }
-            Model3dMultiviewInputs::TaskId { task_id } if task_id.trim().is_empty() => {
-                return Err(TripoError::InvalidParameters {
-                    field: Some(TripoField::Inputs),
-                    reason: TripoValidationReason::Required,
-                    message: "task_id must not be blank".into(),
-                });
-            }
-            Model3dMultiviewInputs::TaskId { .. } => {}
+            Model3dMultiviewInputs::TaskId { task_id } => validate_task_id(task_id)?,
         }
         validate_generation_options(&TripoGenerationOptions {
             model: request.model,