refactor: remove obsolete member management API module

apps/web/supabase/migrations/20260418000003_instructor_availability.sql

@@ -0,0 +1,36 @@
+-- =====================================================
+-- Instructor Availability Check
+--
+-- Returns TRUE if the instructor has no scheduling
+-- conflicts for the requested date/time window.
+-- Optionally excludes a specific session (for edits).
+-- =====================================================
+
+CREATE OR REPLACE FUNCTION public.check_instructor_availability(
+  p_instructor_id uuid,
+  p_session_date date,
+  p_start_time time,
+  p_end_time time,
+  p_exclude_session_id uuid DEFAULT NULL
+)
+RETURNS boolean
+LANGUAGE sql
+STABLE
+SECURITY DEFINER
+SET search_path = ''
+AS $$
+  SELECT NOT EXISTS (
+    SELECT 1
+    FROM public.course_sessions cs
+    JOIN public.courses c ON c.id = cs.course_id
+    WHERE c.instructor_id = p_instructor_id
+      AND cs.session_date = p_session_date
+      AND cs.start_time < p_end_time
+      AND cs.end_time > p_start_time
+      AND (p_exclude_session_id IS NULL OR cs.id != p_exclude_session_id)
+      AND cs.is_cancelled = false
+  );
+$$;
+
+GRANT EXECUTE ON FUNCTION public.check_instructor_availability(uuid, date, time, time, uuid) TO authenticated;
+GRANT EXECUTE ON FUNCTION public.check_instructor_availability(uuid, date, time, time, uuid) TO service_role;