Fix column/card ordering: set COLLATE C on position columns

Postgres en_US.utf8 collation sorts case-insensitively, breaking the
lexicographic fractional indexing. Setting COLLATE "C" ensures pure
byte-order sorting. Applied via setup-collation.sql in entrypoint
after prisma db push.

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

scripts/setup-collation.sql

@@ -0,0 +1,6 @@
+-- Set COLLATE "C" on position columns so fractional indexing sorts correctly.
+-- en_US.utf8 collation is case-insensitive and breaks lexicographic ordering.
+-- This must run after prisma db push since push may reset column types.
+
+ALTER TABLE columns ALTER COLUMN position SET DATA TYPE text COLLATE "C";
+ALTER TABLE cards ALTER COLUMN position SET DATA TYPE text COLLATE "C";