fix(mindspace): 公开页上传图片物化到 static 路径供转发访问

Finish 同步与首次访问时将私有资产 API 图片复制到 public/.tmp-images，
避免其他用户转发链接后因无登录态无法加载页面内图片。

Co-authored-by: Cursor <cursoragent@cursor.com>

mindspace-chat-save.mjs

@@ -50,6 +50,7 @@ export async function materializePrivateAssetsInWorkspaceHtml({
   htmlRelativePath,
   writeBack = false,
 }) {
+  PRIVATE_ASSET_URL_PATTERN.lastIndex = 0;
   const matches = [...String(html).matchAll(PRIVATE_ASSET_URL_PATTERN)];
   if (matches.length === 0) {
     return { html, count: 0, changed: false };
@@ -106,6 +107,55 @@ export async function materializePrivateAssetsInWorkspaceHtml({
   return { html: result, count, changed: true };
 }
 
+export function htmlReferencesPrivateAssets(html) {
+  PRIVATE_ASSET_URL_PATTERN.lastIndex = 0;
+  const found = PRIVATE_ASSET_URL_PATTERN.test(String(html ?? ''));
+  PRIVATE_ASSET_URL_PATTERN.lastIndex = 0;
+  return found;
+}
+
+export async function materializePrivateAssetsInPublicHtmlFiles({
+  pool,
+  storageRoot,
+  h5Root,
+  userId,
+  publishDir,
+  relativePaths = [],
+}) {
+  const materialized = [];
+  const skipped = [];
+  const uniquePaths = [...new Set(relativePaths)].filter(Boolean);
+  for (const htmlRelativePath of uniquePaths) {
+    const htmlPath = path.join(publishDir, htmlRelativePath);
+    let html;
+    try {
+      html = await fs.readFile(htmlPath, 'utf8');
+    } catch {
+      skipped.push(htmlRelativePath);
+      continue;
+    }
+    if (!htmlReferencesPrivateAssets(html)) {
+      skipped.push(htmlRelativePath);
+      continue;
+    }
+    const result = await materializePrivateAssetsInWorkspaceHtml({
+      pool,
+      storageRoot,
+      h5Root,
+      userId,
+      html,
+      htmlRelativePath,
+      writeBack: true,
+    });
+    if (result.changed) {
+      materialized.push({ relativePath: htmlRelativePath, count: result.count });
+    } else {
+      skipped.push(htmlRelativePath);
+    }
+  }
+  return { materialized, skipped };
+}
+
 export async function repairMissingHtmlAssetReferences({ pool, userId, sourceContent, html }) {
   const collectIds = (text) => [
     ...new Set([...String(text).matchAll(PRIVATE_ASSET_URL_PATTERN)].map((match) => match[1])),