发布页媒体提交只合成一次

- buildPublishGameMetadata / buildPublishMediaParts 改为接收调用方算好的 submission，元数据槽位与上传 part 单一来源

src/components/game-distribution/GamePublishPage.tsx

@@ -31,6 +31,7 @@ import {
 import {
   buildGamePublishMediaSubmission,
   type GamePublishImage,
+  type GamePublishMediaSubmission,
   revokeGamePublishImagePreview,
 } from './gamePublishAssets';
 import { GamePublishClientGuide } from './GamePublishClientGuide';
@@ -313,11 +314,10 @@ export function GamePublishPage({
    * 组装提交给服务端的资料 DTO。
    *
    * 媒体槽位只描述来源：本地新图写 `null`（由对应的二进制 part 补位），沿用线上图写 objectKey；
-   * 原始字节另由 `buildPublishMediaParts` 作为 multipart part 提交。两者共用
-   * `buildGamePublishMediaSubmission`，槽位映射与 part 组装不会各改各的。
+   * 原始字节另由 `buildPublishMediaParts` 作为 multipart part 提交。两者消费调用方算好的
+   * 同一个 `buildGamePublishMediaSubmission` 结果，槽位映射与 part 组装不会各改各的。
    */
-  function buildPublishGameMetadata() {
-    const media = buildGamePublishMediaSubmission(coverImage, screenshotImages);
+  function buildPublishGameMetadata(media: GamePublishMediaSubmission) {
     return {
       title: title.trim(),
       summary: summary.trim(),
@@ -332,8 +332,8 @@ export function GamePublishPage({
     };
   }
 
-  function buildPublishMediaParts() {
-    return buildGamePublishMediaSubmission(coverImage, screenshotImages).parts;
+  function buildPublishMediaParts(media: GamePublishMediaSubmission) {
+    return media.parts;
   }
 
   /** 是否已有封面：本地新图或沿用线上图都算。 */
@@ -431,8 +431,12 @@ export function GamePublishPage({
     try {
       const prepared = await prepareGamePackage(packageFile);
       const updateKey = resolvePublishKey();
-      const gameMetadata = buildPublishGameMetadata();
-      const media = buildPublishMediaParts();
+      const submission = buildGamePublishMediaSubmission(
+        coverImage,
+        screenshotImages,
+      );
+      const gameMetadata = buildPublishGameMetadata(submission);
+      const media = buildPublishMediaParts(submission);
       const version = await createGameVersion(
         updateContext.gameId,
         {
@@ -511,8 +515,12 @@ export function GamePublishPage({
     setError('');
     try {
       const prepared = await prepareGamePackage(packageFile);
-      const gameMetadata = buildPublishGameMetadata();
-      const media = buildPublishMediaParts();
+      const submission = buildGamePublishMediaSubmission(
+        coverImage,
+        screenshotImages,
+      );
+      const gameMetadata = buildPublishGameMetadata(submission);
+      const media = buildPublishMediaParts(submission);
       const publishKey = resolvePublishKey();
       const game = await createGame(gameMetadata, `${publishKey}:game`, media);
       const version = await createGameVersion(