fix(wechat): scrub image_url from sessions and harden vision handoff.

Strip image_url from persisted session payloads, keep image turns scoped to the active request, and align proxy/vision/page-data paths so WeChat image history does not leak into fresh sessions.

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

public/assets/page-data-client.js

@@ -106,6 +106,9 @@
       listRows: function (dataset, query) {
         return request('GET', buildDataPath(apiBase, pageId, dataset), { query: query || {} });
       },
+      readRows: function (dataset, query) {
+        return request('GET', buildDataPath(apiBase, pageId, dataset), { query: query || {} });
+      },
       getSchema: function (dataset) {
         return request('GET', buildDataPath(apiBase, pageId, dataset, 'schema'));
       },