fix(lesson-editor): redirect to edit URL after first draft save to prevent duplicate lessons

When creating a new lesson and clicking Save Draft, the context had no
initialData so every subsequent save called createLesson again instead of
updateLesson. Fix: redirect to /lessons/:id after the first successful create
regardless of publish state, so the edit page loads with initialData set and
all further saves hit updateLesson.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: guillermoscript

components/teacher/lesson-editor/lesson-editor-context.tsx

@@ -167,6 +167,10 @@ export function LessonEditorProvider({
 
       if (publish) {
         router.push(`/dashboard/teacher/courses/${courseId}`)
+      } else if (!initialData) {
+        // New lesson saved as draft — redirect to edit URL so subsequent saves
+        // call updateLesson instead of createLesson (prevents duplicates)
+        router.push(`/dashboard/teacher/courses/${courseId}/lessons/${result.data.lessonId}`)
       } else {
         setSaveSuccess(true)
         setLoading(false)