过滤 canonical 草稿中的空白输入 part

在统一 user item 转换入口移除纯空白 input_text，覆盖恢复草稿和所有提交路径。

apps/ai-game-creator-shell/src/features/project-workspace/resourceReferences.ts

@@ -120,7 +120,9 @@ export function chatComposerDraftToDirectCodexUserItem(
 ): DirectCodexUserItem {
   let content: DirectCodexUserContentPart[];
   if (draft.content?.length) {
-    content = draft.content;
+    content = draft.content.filter(
+      (part) => part.type !== 'input_text' || part.text.trim().length > 0,
+    );
   } else if (draft.references.length > 0) {
     content = [
       ...(draft.text