feat(db): add migration for volume column type change

- Create migration 0002_alter_volume_type.sql to change volume from TEXT to INTEGER
- Update docker-compose to run all migrations automatically using env variables
- Enables proper numeric sorting of volumes (1, 2, 3 instead of 01, 02, 03)

infra/migrations/0002_alter_volume_type.sql

@@ -0,0 +1,4 @@
+-- Migration: Change volume column type from TEXT to INTEGER
+-- This allows proper numeric sorting and removes leading zeros
+
+ALTER TABLE books ALTER COLUMN volume TYPE INTEGER USING volume::integer;