issue #40: add notification table

src/db/migrations/0000_cold_old_lace.sql

src/db/migrations/0000_cooing_doorman.sql

src/db/migrations/meta/0000_snapshot.json

src/db/migrations/meta/_journal.json

src/db/relations/notification.relation.ts

src/db/repo/notification.repo.ts

src/db/schema/index.ts

src/db/seed.ts

src/db/seeds/user-stats.seed.ts

src/db/seeds/user.seed.ts

src/index.ts

src/routes/notification.route.ts

src/services/notification.service.ts