feat(baoyu-post-to-wechat): add multi-account support

Support multiple WeChat Official Accounts via EXTEND.md accounts block.
Each account gets isolated Chrome profile, credential resolution chain
(inline → prefixed env → unprefixed env), and --account CLI arg.

skills/baoyu-post-to-wechat/scripts/cdp.ts

@@ -1,4 +1,5 @@
 import { execSync, type ChildProcess } from 'node:child_process';
+import path from 'node:path';
 import process from 'node:process';
 
 import {
@@ -80,6 +81,11 @@ export function getDefaultProfileDir(): string {
   });
 }
 
+export function getAccountProfileDir(alias: string): string {
+  const base = getDefaultProfileDir();
+  return path.join(path.dirname(base), `wechat-${alias}`);
+}
+
 export interface ChromeSession {
   cdp: CdpConnection;
   sessionId: string;