fix: update X link to @MulticaAI in readme and landing page

Replace outdated x.com/multica_hq with x.com/MulticaAI in:
- README.zh-CN.md
- Landing page shared config
- Landing page en/zh i18n files

README.zh-CN.md

@@ -20,7 +20,7 @@
 [![CI](https://github.com/multica-ai/multica/actions/workflows/ci.yml/badge.svg)](https://github.com/multica-ai/multica/actions/workflows/ci.yml)
 [![GitHub stars](https://img.shields.io/github/stars/multica-ai/multica?style=flat)](https://github.com/multica-ai/multica/stargazers)
 
-[官网](https://multica.ai) · [云服务](https://multica.ai/app) · [X](https://x.com/multica_hq) · [自部署指南](SELF_HOSTING.md) · [参与贡献](CONTRIBUTING.md)
+[官网](https://multica.ai) · [云服务](https://multica.ai/app) · [X](https://x.com/MulticaAI) · [自部署指南](SELF_HOSTING.md) · [参与贡献](CONTRIBUTING.md)
 
 **[English](README.md) | 简体中文**
 

apps/web/features/landing/components/shared.tsx

@@ -1,7 +1,7 @@
 import { cn } from "@multica/ui/lib/utils";
 
 export const githubUrl = "https://github.com/multica-ai/multica";
-export const twitterUrl = "https://x.com/multica_hq";
+export const twitterUrl = "https://x.com/MulticaAI";
 
 export function GitHubMark({ className }: { className?: string }) {
   return (

apps/web/features/landing/i18n/en.ts

@@ -230,7 +230,7 @@ export const en: LandingDict = {
         links: [
           { label: "Documentation", href: githubUrl },
           { label: "API", href: githubUrl },
-          { label: "X (Twitter)", href: "https://x.com/multica_hq" },
+          { label: "X (Twitter)", href: "https://x.com/MulticaAI" },
         ],
       },
       company: {

apps/web/features/landing/i18n/zh.ts

@@ -230,7 +230,7 @@ export const zh: LandingDict = {
         links: [
           { label: "\u6587\u6863", href: githubUrl },
           { label: "API", href: githubUrl },
-          { label: "X (Twitter)", href: "https://x.com/multica_hq" },
+          { label: "X (Twitter)", href: "https://x.com/MulticaAI" },
         ],
       },
       company: {