fix(hub): strip card markdown images + prefer inline ![] over send_file

Feishu interactive markdown rejects ![](http...) without image_key
(error 230099 empty/missing imagekey). Always mask residual image md in
card builders; skip img tags with empty keys; skip inline-code examples;
fetch remote images with a browser UA and without env HTTP_PROXY.
Steer the agent: use ![alt](workspace-path) for 图文, send_file only for
downloadable attachments.

Release v0.0.37.

hub/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@paradigm/hub",
-  "version": "0.0.36",
+  "version": "0.0.37",
   "private": true,
   "type": "module",
   "engines": {