fix(wujie): use placeholder origin for URL rewrite to avoid path duplication

[Gaubee]

Problem

Remote miniapp (rwa-hub) requests are being rewritten incorrectly:

Before (wrong):

Request: /assets/main.js
Rewritten: https://bioforestchain.github.io/KeyApp/webapp/miniapps/rwa-hub/KeyApp/webapp/miniapps/rwa-hub/assets/main.js

After (correct):

Request: /assets/main.js
Rewritten: https://bioforestchain.github.io/KeyApp/webapp/miniapps/rwa-hub/assets/main.js

Root Cause

The old code used string concatenation which duplicated the path:

const rewrittenUrl = `${origin}${parsedReqUrl.pathname}...`;
// origin = https://bioforestchain.github.io/KeyApp/webapp/miniapps/rwa-hub
// pathname = /KeyApp/webapp/miniapps/rwa-hub/assets/main.js
// Result: path duplicated!

Fix

Use placeholder origin approach to properly normalize the URL:

const normalized = new URL(
  parsedReqUrl.pathname + parsedReqUrl.search + parsedReqUrl.hash,
  PLACEHOLDER_ORIGIN + '/',
);
const rewrittenUrl = normalized.href.replace(PLACEHOLDER_ORIGIN + '/', targetBase);

This ensures the pathname is correctly resolved relative to the target base URL.