docs(readme): 子域名改名为 gitea-mcp.zhengchentao.win

域名规划统一：MCP 服务子域名与 repo 名一致。
- git-mcp.zhengchentao.win → gitea-mcp.zhengchentao.win

README.md

@@ -10,7 +10,7 @@ OAuth via nas-auth (DCR + PKCE + JWT HS256), admin PAT held internally — Claud
        │
        │ ① GET /.well-known/oauth-authorization-server
        ↓
-  git-mcp.zhengchentao.win   ←── this service
+  gitea-mcp.zhengchentao.win   ←── this service
        │
        │ ② DCR + PKCE auth flow redirect
        ↓
@@ -22,7 +22,7 @@ OAuth via nas-auth (DCR + PKCE + JWT HS256), admin PAT held internally — Claud
        │
        │ ④ POST /mcp  (MCP Streamable HTTP)
        ↓
-  git-mcp.zhengchentao.win
+  gitea-mcp.zhengchentao.win
        │ Bearer <GITEA_ADMIN_PAT>
        ↓
   git.zhengchentao.win       ←── Gitea