feat(06-01): add migration 007 setup_completed column and backfill

- ALTER TABLE profiles ADD COLUMN setup_completed boolean NOT NULL DEFAULT false
- Backfill existing users with categories OR template items to true
- UNION covers edge case users with template items but no categories

supabase/migrations/007_setup_completed.sql

@@ -0,0 +1,18 @@
+-- Migration 007: Add setup_completed to profiles
+-- New signups default to false (not set up).
+-- Existing users who have any categories are backfilled to true (already set up).
+-- Wider backfill also includes users with template items to protect against
+-- edge case where user created template items but skipped category creation.
+
+ALTER TABLE profiles
+  ADD COLUMN setup_completed boolean NOT NULL DEFAULT false;
+
+-- Backfill: users with categories OR template items are considered set up
+UPDATE profiles
+SET setup_completed = true
+WHERE id IN (
+  SELECT DISTINCT user_id FROM categories
+  UNION
+  SELECT t.user_id FROM templates t
+  INNER JOIN template_items ti ON ti.template_id = t.id
+);