chore: 修复登录页与前端开发服务器配置

- vite dev server 端口改为 5000 并启用 strictPort，端口冲突时拒绝启动
- AGENTS.md 更新前端目录结构说明（移除已删除的 ERB/enterprise 目录）及端口文档
- v3 登录页精简：移除 useBranding/globalConfig 依赖，去掉忘记密码链接
- 中文登录表单翻译优化（Email → 电子邮件）

frontend/app/javascript/dashboard/i18n/locale/zh_CN/login.json

@@ -2,8 +2,8 @@
   "LOGIN": {
     "TITLE": "登录到Chatwoot",
     "EMAIL": {
-      "LABEL": "Email",
-      "PLACEHOLDER": "实例 {'@'}companyname.com",
+      "LABEL": "电子邮件",
+      "PLACEHOLDER": "电子邮件",
       "ERROR": "请输入一个有效的电子邮件"
     },
     "PASSWORD": {

frontend/app/javascript/v3/views/login/Index.vue

@@ -1,13 +1,11 @@
 <script>
 // utils and composables
 import { login } from '../../api/auth';
-import { mapGetters } from 'vuex';
 import { useAlert } from 'dashboard/composables';
 import { required, email } from '@vuelidate/validators';
 import { useVuelidate } from '@vuelidate/core';
 import { SESSION_STORAGE_KEYS } from 'dashboard/constants/sessionStorage';
 import SessionStorage from 'shared/helpers/sessionStorage';
-import { useBranding } from 'shared/composables/useBranding';
 
 // components
 import SimpleDivider from '../../components/Divider/SimpleDivider.vue';
@@ -46,9 +44,7 @@ export default {
     authError: { type: String, default: '' },
   },
   setup() {
-    const { replaceInstallationName } = useBranding();
     return {
-      replaceInstallationName,
       v$: useVuelidate(),
     };
   },
@@ -84,7 +80,6 @@ export default {
     };
   },
   computed: {
-    ...mapGetters({ globalConfig: 'globalConfig/get' }),
     allowedLoginMethods() {
       return window.chatwootConfig.allowedLoginMethods || ['email'];
     },
@@ -227,14 +222,8 @@ export default {
 
 <template>
   <main
-    class="flex flex-col w-full min-h-screen py-20 bg-n-brand/5 dark:bg-n-background sm:px-6 lg:px-8"
+    class="flex flex-col items-center justify-center w-full min-h-screen bg-n-brand/5 dark:bg-n-background sm:px-6 lg:px-8"
   >
-    <section class="max-w-5xl mx-auto">
-      <h2 class="text-3xl font-medium text-center text-n-slate-12">
-        {{ replaceInstallationName($t('LOGIN.TITLE')) }}
-      </h2>
-    </section>
-
     <!-- MFA Verification Section -->
     <section v-if="mfaRequired" class="mt-11">
       <MfaVerification
@@ -300,17 +289,7 @@ export default {
             :placeholder="$t('LOGIN.PASSWORD.PLACEHOLDER')"
             :has-error="v$.credentials.password.$error"
             @input="v$.credentials.password.$touch"
-          >
-            <p v-if="!globalConfig.disableUserProfileUpdate">
-              <router-link
-                to="auth/reset/password"
-                class="text-sm text-link"
-                tabindex="4"
-              >
-                {{ $t('LOGIN.FORGOT_PASSWORD') }}
-              </router-link>
-            </p>
-          </FormInput>
+          />
           <NextButton
             lg
             type="submit"