feat: Implement lesson access control logic including enrollment, prerequisite, and quiz completion checks.

Backend/src/types/CoursesStudent.types.ts

@@ -286,4 +286,23 @@ export interface SaveVideoProgressBody {
 
 export interface EnrollCourseBody {
     course_id: number;
-}
+}
+
+export interface CompleteLessonInput {
+    token: string;
+    lesson_id: number;
+}
+
+export interface CompleteLessonResponse {
+    code: number;
+    message: string;
+    data?: {
+        lesson_id: number;
+        is_completed: boolean;
+        completed_at: Date;
+        course_progress_percentage: number;
+        is_course_completed: boolean;
+        next_lesson_id: number | null;
+        certificate_issued?: boolean;
+    };
+}