feat: implement core e-learning pages, course composable, and i18n localization.

Frontend-Learner/pages/course/[id].vue

@@ -13,7 +13,7 @@ definePageMeta({
 const route = useRoute()
 // ดึง courseId จาก URL params (แปลงเป็น integer)
 const courseId = computed(() => parseInt(route.params.id as string))
-const { fetchCourseById, enrollCourse } = useCourse()
+const { fetchCourseById, enrollCourse, getLocalizedText } = useCourse()
 
 // ใช้ useAsyncData ดึงข้อมูลคอร์ส Server-side rendering (SSR)
 // Key: 'course-{id}' เพื่อให้ cache แยกกันตาม ID
@@ -54,12 +54,6 @@ const handleEnroll = async () => {
 }
 
 
-const getLocalizedText = (text: string | { th: string; en: string } | undefined | null) => {
-  if (!text) return ''
-  if (typeof text === 'string') return text
-  // @ts-ignore
-  return text.th || text.en || ''
-}
 
 
 useHead({