fix(wechat): repair share preview on disk for sanitized delivery artifacts

Production WeChat delivery strips localPath from artifacts, so share-preview
auto-repair never wrote back to HTML. Resolve paths via publishDir +
relativePath, repair at materialize and delivery prep, and pass h5Root from
Portal so page.generate can patch missing meta before sending links.

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

wechat/verify/generated-thumbnail.mjs

@@ -5,6 +5,7 @@ import {
   parseMindspaceCoverMeta,
   upsertMindspaceCoverMeta,
 } from '../../mindspace-cover-meta.mjs';
+import { resolveArtifactLocalPath } from './page-artifact.mjs';
 
 const RASTER_MIME_PATTERN = /^image\/(?:png|jpeg|webp)$/i;
 
@@ -121,7 +122,11 @@ export function isWechatAuxiliaryPageArtifact(artifact) {
     || /<[^>]+data-mindspace-page-role=["'](?:admin|auxiliary)["']/i.test(html);
 }
 
-export function verifyFreshWechatPageThumbnails(artifacts = [], images = []) {
+export function verifyFreshWechatPageThumbnails(
+  artifacts = [],
+  images = [],
+  { publishDir = '' } = {},
+) {
   if (!Array.isArray(artifacts) || artifacts.length === 0) {
     return { ok: false, reason: 'missing_page_artifact', matches: [] };
   }
@@ -136,7 +141,7 @@ export function verifyFreshWechatPageThumbnails(artifacts = [], images = []) {
   const usedJobs = new Set();
   const matches = [];
   for (const artifact of eligibleArtifacts) {
-    const localPath = String(artifact?.localPath ?? '').trim();
+    const localPath = resolveArtifactLocalPath(artifact, publishDir);
     if (!localPath || !fs.existsSync(localPath)) {
       return { ok: false, reason: 'missing_page_artifact', artifact, matches, skippedArtifacts };
     }