feat(license): 退出授权 / 释放本实例（确认后 deactivate）

设置→授权 Pro 态管理员可退出：在线 LIC- 先调 opsx deactivate（含 activation_token），成功才清本地；失败保留现状。LICOFF- 仅解本机并提示后台名额可能仍占。禁静默清码。

frontend/src/i18n/locales/en/license.ts

@@ -21,6 +21,14 @@ export default {
   activating: 'Activating…',
   activated: 'Pro activated — all features unlocked',
   activateFailed: 'Activation failed',
+  deactivate: 'Deactivate / release this instance',
+  deactivateConfirmTitle: 'Deactivate license?',
+  deactivateConfirmDesc: 'This releases the seat for this instance and returns the machine to Free. Online keys notify the license server first; on failure local state is kept (never silently cleared).',
+  deactivateConfirm: 'Confirm deactivate',
+  deactivating: 'Deactivating…',
+  deactivated: 'License deactivated — this machine is Free again',
+  deactivateFailed: 'Deactivation failed',
+  deactivateOfflineNote: 'Local offline license unbound. The server seat may still be occupied — ask ops to clear it if needed.',
   legacyBanner: 'Legacy HMAC keys are in a migration window. Please switch to a LIC- / LICOFF- key. Old keys stay valid until the window ends — never silently invalidated.',
   graceBanner: 'Offline grace: {{days}} day(s) left. Reconnect to re-verify.',
   status: {