fix: add Enter key support to login and exclude Windows from Unix tests

Part 1: Login UX Enhancement
- Add form submission on Enter key press
- Auto-focus username field on page load
- Add @pressEnter handlers to both input fields
- Import ref and onMounted from Vue composition API

Part 2: Windows Build Fix
- Add build tags to limits_test.go to exclude from Windows builds
- Fixes golang.org/x/sys/unix import error on Windows
- Aligns with existing limits.go build constraints

Tested on Windows 11:
- Go 1.24.6: Build succeeds without errors
- Chrome/Edge: Enter key and auto-focus work correctly

Fixes #1405

Author: ankitsharma101

pkg/common/util/os/limits_test.go

@@ -1,3 +1,6 @@
+//go:build !windows
+// +build !windows
+
 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with

ui-vue3/src/Login.vue

@@ -16,7 +16,7 @@
 -->
 
 <script setup lang="ts">
-import { reactive } from 'vue'
+import { reactive, ref, onMounted } from 'vue'
 import { login } from '@/api/service/login'
 import { useRoute, useRouter } from 'vue-router'
 import { updateAuthState } from '@/utils/AuthUtil'
@@ -34,6 +34,12 @@ const route = useRoute()
 const redirect: any = route.query.redirect || '/'
 const meshStore = useMeshStore()
 
+const usernameInputRef = ref()
+
+onMounted(() => {
+  usernameInputRef.value?.focus()
+})
+
 function loginHandle() {
   let formData = new FormData()
   formData.append('user', userinfo.username)
@@ -68,15 +74,23 @@ function loginHandle() {
             name="username"
             :rules="[{ required: true }]"
           >
-            <a-input type="" v-model:value="userinfo.username"></a-input>
+            <a-input 
+              ref="usernameInputRef"
+              v-model:value="userinfo.username"
+              @pressEnter="loginHandle"
+            ></a-input>
           </a-form-item>
           <a-form-item
             class="item"
             :label="$t('loginDomain.password')"
             name="password"
             :rules="[{ required: true }]"
           >
-            <a-input type="password" v-model:value="userinfo.password"></a-input>
+            <a-input 
+              type="password" 
+              v-model:value="userinfo.password"
+              @pressEnter="loginHandle"
+            ></a-input>
           </a-form-item>
           <a-form-item class="item" label="">
             <a-button @click="loginHandle" size="large" type="primary" class="login-btn"