feat(license): dual-path opsx-licence client alongside HMAC

Wire LIC-/LICOFF- activate/verify/heartbeat to licence.rlwj.cn/api,
keep legacy HMAC accepted with deprecation banner, add instance_id
fingerprint and licensing docs (product lokistack still needs admin create).

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

@@ -7,18 +7,21 @@ export default {
   expiry: 'Valid until',
   customer: 'Licensed to',
   seats: 'Seats',
+  instances: 'Instance limit',
   permanent: 'perpetual',
   personalTitle: 'Personal',
   teamTitle: 'Team',
-  keyPlaceholder: 'Enter license key to activate Pro…',
+  keyPlaceholder: 'Enter LIC- / LICOFF- key to activate Pro…',
   activate: 'Activate',
   activating: 'Activating…',
   activated: 'Pro activated — all features unlocked',
   activateFailed: 'Activation failed',
+  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.',
   gate: {
     title: '{{feature}} is a Pro feature',
     desc: 'Upgrade to Pro to unlock the full analytics suite. The Free plan keeps log query, deployment management and user/LDAP administration.',
-    keyPlaceholder: 'Paste license key…',
+    keyPlaceholder: 'Paste LIC- / LICOFF- key…',
     activate: 'Activate',
     toSettings: 'Open settings',
     freeHint: 'Free plan includes: log query / deployment management / users / LDAP',