step 3: Make UUID columns NOT NULL

- Add migration 000008: Add NOT NULL constraints to UUID columns
- This completes the dual-write phase

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

internal/db/migrations/000008_make_uuid_required.up.sql

@@ -0,0 +1,7 @@
+-- Migration: Make UUID columns NOT NULL
+
+-- Make UUID required on soundtrack
+ALTER TABLE soundtrack ALTER COLUMN uuid SET NOT NULL;
+
+-- Make UUID required on song
+ALTER TABLE song ALTER COLUMN uuid SET NOT NULL;