adding starting and ending indexes to pdfs

This will allow us to keep the library smart with the ability to split
our pdfs up into multiple presetations

migrations/20251020184333_add_starting_index_and_ending_index_to_presentations_table.sql

@@ -0,0 +1,6 @@
+-- Add migration script here
+ALTER TABLE presentations
+ADD COLUMN starting_index INTEGER;
+
+ALTER TABLE presentations
+ADD COLUMN ending_index INTEGER;