Move the empty-string checks migration after the last one hosted applied

[davidtaing]

Why

Every Vercel Deploy run since #152 merged has failed at the migration step:

Found local migration files to be inserted before the last migration on remote database.
Rerun the command with --include-all flag to apply these migrations:
supabase/migrations/20260912133715_add_empty_string_checks.sql

#152's migration is timestamped 20260912133715, but it merged after #154's 20260914080000 had already been applied to the hosted project. db push will not insert a migration before the last one the remote has applied, so production is stuck at the commit before #152.

What

Renames the file to 20261007100000_add_empty_string_checks.sql. The contents are unchanged. Hosted never applied the old name, so its schema_migrations has no entry to reconcile.

I chose a rename over adding --include-all to the deploy step. AGENTS.md treats that flag as a deliberate repair, and leaving it on would also let a future out-of-order migration through without anyone noticing. The rename also keeps local replay order the same as the order hosted applied the migrations in.

Checked

• pnpm db:reset applies every migration in the new order without errors.
• pnpm test:db: 18 files and 271 tests passed, exit 0.

Not checked: whether any hosted row already has a blank practitioners.name or practitioner_contacts.contact_email. If one does, the constraint will fail to add and the push will fail again, for a different reason.