fix: superadmin assignments show ENV badge, block UI revoke

Superadmin role (level 999) is managed via env config only. Hide X
button for superadmin assignments and show ENV badge instead. Filter
superadmin from assignable roles dropdown. Add envManaged translation
to all 4 locales.

src/locales/en.json

@@ -3227,6 +3227,7 @@
       "system": "System",
       "permanent": "Permanent",
       "expired": "expired",
+      "envManaged": "Managed via ADMIN_IDS / ADMIN_EMAILS in env",
       "revoke": "Revoke",
       "revokeAriaLabel": "Revoke role {{role}} from {{user}}",
       "table": {

src/locales/fa.json

@@ -2968,6 +2968,7 @@
       "system": "سیستم",
       "permanent": "دائمی",
       "expired": "منقضی شده",
+      "envManaged": "مدیریت از طریق ADMIN_IDS / ADMIN_EMAILS در env",
       "revoke": "لغو",
       "revokeAriaLabel": "لغو نقش {{role}} از {{user}}",
       "table": {

src/locales/ru.json

@@ -3773,6 +3773,7 @@
       "system": "Система",
       "permanent": "Бессрочно",
       "expired": "истекло",
+      "envManaged": "Управляется через ADMIN_IDS / ADMIN_EMAILS в env",
       "revoke": "Отозвать",
       "revokeAriaLabel": "Отозвать роль {{role}} у {{user}}",
       "table": {

src/locales/zh.json

@@ -2967,6 +2967,7 @@
       "system": "系统",
       "permanent": "永久",
       "expired": "已过期",
+      "envManaged": "通过 ADMIN_IDS / ADMIN_EMAILS 环境变量管理",
       "revoke": "撤销",
       "revokeAriaLabel": "撤销 {{user}} 的角色 {{role}}",
       "table": {