fix(dashboard): redirect to course start after auto-enroll (#741)

* fix(dashboard): redirect to course start after auto-enroll

After successful enrollment on the org-site enroll page, verified users
were always sent to /lms because resolvePostEnrollRedirect was hardcoded.
Restore the API redirectTo target (/courses/:id/lessons?next=true) so
students land on their first lesson, with /course/:slug as fallback.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): match LMS continue path after auto-enroll

Use the same student course continue URL as the LMS home page
(/courses/:id/lessons?next=true) via a shared helper, and navigate with
goto instead of a hard reload or org-site /course/:slug fallback.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

---------
Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

apps/dashboard/src/lib/features/course/utils/student-course-navigation.ts

@@ -0,0 +1,3 @@
+export function getStudentCourseContinuePath(courseId: string): string {
+  return `/courses/${courseId}/lessons?next=true`;
+}