fix(wechat): rotate image_url-poisoned sessions for report follow-ups

Goose cannot persist historical image scrub (PUT 405), so DeepSeek rejects
image_url on the next turn. Reattach the recent report image and rotate to a
fresh session instead of treating the follow-up as a missing page source.

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

tkmind-proxy.test.mjs

@@ -1707,6 +1707,8 @@ test('submitSessionReplyForUser applies the shared Qwen vision preprocessing pat
     const forwardedText = replyBodies[0]?.user_message?.content?.[0]?.text ?? '';
     assert.match(forwardedText, /Qwen VL 图片描述/);
     assert.match(forwardedText, /一件蓝色产品/);
+    assert.equal(replyBodies[0]?.user_message?.metadata?.imageUrls, undefined);
+    assert.ok(Array.isArray(replyBodies[0]?.user_message?.metadata?.archivedImageUrls));
   });
 });