打磨封面与截图的文件选择交互

- 网页发布页：封面与截图改用透明 input 覆盖自定义胶囊按钮，点击命中原生控件；上传后不再出现「未选择任何文件」与「已选择」互相矛盾的状态。
- AGC 发布面板：同一处理，按钮文案随状态在「选择封面图片 / 更换封面图片」「添加截图 / 截图已满 6 张」之间切换。
- 文档：实施计划补充真实浏览器发布链路证据（网页上传封面 → my-games 待审 → 版本 frozenMetadata 指向本次上传素材）与交互打磨记录。

src/components/game-distribution/GamePublishPage.tsx

@@ -851,15 +851,26 @@ export function GamePublishPage({
             <div className="game-publish-media__copy">
               <label className="game-publish-field">
                 游戏封面（必需）
-                <input
-                  ref={coverInputRef}
-                  type="file"
-                  accept={GAME_PUBLISH_IMAGE_ACCEPT}
-                  disabled={isResumingDraft || isSubmitting || isUploadingAsset}
-                  onChange={(event) => {
-                    void handleCoverSelected(event.target.files?.[0] ?? null);
-                  }}
-                />
+                {/*
+                  原生 file 控件在清空 value 后会显示“未选择任何文件”，与下方的“已选择”提示互相
+                  矛盾；上传后必须清空 value 才能重选同一张图，所以这里改用自定义触发按钮。
+                */}
+                <span className="game-publish-media__picker">
+                  <input
+                    ref={coverInputRef}
+                    type="file"
+                    accept={GAME_PUBLISH_IMAGE_ACCEPT}
+                    disabled={
+                      isResumingDraft || isSubmitting || isUploadingAsset
+                    }
+                    onChange={(event) => {
+                      void handleCoverSelected(event.target.files?.[0] ?? null);
+                    }}
+                  />
+                  <span className="game-publish-media__pick">
+                    {coverAsset ? '更换封面图片' : '选择封面图片'}
+                  </span>
+                </span>
                 <span className="game-publish-hint">
                   {coverAsset?.assetObjectId
                     ? `已选择「${coverAsset.name}」；重新选择即可替换本次发布的封面。`
@@ -883,23 +894,30 @@ export function GamePublishPage({
           <div className="game-publish-media__screenshots">
             <label className="game-publish-field">
               {`游戏截图（可选，最多 ${MAX_GAME_SCREENSHOTS} 张）`}
-              <input
-                ref={screenshotInputRef}
-                type="file"
-                accept={GAME_PUBLISH_IMAGE_ACCEPT}
-                multiple
-                disabled={
-                  isResumingDraft ||
-                  isSubmitting ||
-                  isUploadingAsset ||
-                  screenshotAssets.length >= MAX_GAME_SCREENSHOTS
-                }
-                onChange={(event) => {
-                  void handleScreenshotsSelected(
-                    Array.from(event.target.files ?? []),
-                  );
-                }}
-              />
+              <span className="game-publish-media__picker">
+                <input
+                  ref={screenshotInputRef}
+                  type="file"
+                  accept={GAME_PUBLISH_IMAGE_ACCEPT}
+                  multiple
+                  disabled={
+                    isResumingDraft ||
+                    isSubmitting ||
+                    isUploadingAsset ||
+                    screenshotAssets.length >= MAX_GAME_SCREENSHOTS
+                  }
+                  onChange={(event) => {
+                    void handleScreenshotsSelected(
+                      Array.from(event.target.files ?? []),
+                    );
+                  }}
+                />
+                <span className="game-publish-media__pick">
+                  {screenshotAssets.length >= MAX_GAME_SCREENSHOTS
+                    ? '截图已满 6 张'
+                    : '添加截图'}
+                </span>
+              </span>
               <span className="game-publish-hint">
                 截图会按选择顺序展示在详情页；不需要可以留空。
               </span>

src/components/game-distribution/gameDistribution.css

@@ -924,6 +924,52 @@
   font-size: 0.72rem;
   font-weight: 600;
 }
+.game-publish-media__picker {
+  position: relative;
+  display: inline-flex;
+  align-items: center;
+}
+/* 透明 input 覆盖在触发按钮上：真实点击永远命中原生控件，自定义文案只负责显示。 */
+.game-publish-media__picker input[type='file'] {
+  position: absolute;
+  inset: 0;
+  width: 100%;
+  height: 100%;
+  margin: 0;
+  padding: 0;
+  border: 0;
+  opacity: 0;
+  cursor: pointer;
+}
+.game-publish-media__pick {
+  display: inline-flex;
+  pointer-events: none;
+  align-items: center;
+  padding: 0.35rem 0.85rem;
+  border: 1px solid var(--platform-surface-border);
+  border-radius: 999px;
+  background: var(--platform-panel-fill);
+  color: var(--platform-text-strong);
+  font-size: 0.74rem;
+  font-weight: 600;
+  cursor: pointer;
+  transition: 160ms ease;
+}
+.game-publish-media__picker:hover .game-publish-media__pick {
+  border-color: rgba(199, 101, 61, 0.45);
+}
+.game-publish-media__picker
+  input[type='file']:focus-visible
+  + .game-publish-media__pick {
+  outline: 2px solid rgba(199, 101, 61, 0.35);
+  outline-offset: 2px;
+}
+.game-publish-media__picker
+  input[type='file']:disabled
+  + .game-publish-media__pick {
+  opacity: 0.55;
+  cursor: not-allowed;
+}
 .game-publish-media__screenshots {
   display: grid;
   gap: 0.6rem;