feat(lms): add student certificates page and sidebar nav (#696)

* feat(lms): add student certificates page and sidebar nav

Add a Certificates item to the student LMS sidebar that lists courses
where the student has earned a certificate. Each course card includes a
View Certificate action linking to the existing per-course certificate
page.

* refactor: reuse isOrgOnFreePlan helper from org store

* chore(i18n): add certificates translations for all locales

---------

apps/dashboard/src/lib/features/ui/navigation/lms-navigation.ts

@@ -1,4 +1,5 @@
 import {
+  CertificateIcon,
   CommunityIcon,
   CourseIcon,
   ExerciseIcon,
@@ -11,6 +12,7 @@ import {
 import type { AccountOrg } from '$features/app/types';
 import type { Component } from 'svelte';
 import { isActive } from '$lib/utils/functions/app';
+import { isOrgOnFreePlan } from '$lib/utils/store/org';
 
 export interface NavItem {
   title: string;
@@ -57,6 +59,13 @@ export const baseNavConfig: NavItemConfig[] = [
     icon: CourseIcon,
     matchPattern: '^/lms/mylearning(/.*)?$'
   },
+  {
+    titleKey: 'lms_navigation.certificates',
+    path: '/certificates',
+    icon: CertificateIcon,
+    matchPattern: '^/lms/certificates(/.*)?$',
+    show: (currentOrg) => !isOrgOnFreePlan(currentOrg)
+  },
   {
     titleKey: 'lms_navigation.explore',
     path: '/explore',