DB optimization: pool, golang-migrate, consolidate to single Postgres

- Fix DB_NAME=db_yal -> mydb in api_yal .env
- Add connection pool (MaxOpenConns 25, MaxIdleConns 10, ConnMaxLifetime 30m)
- Replace GORM AutoMigrate with golang-migrate in api_yal and api_bb
- Create embedded SQL migrations for both APIs
- Add DB_SCHEMA support to api_bb config
- Consolidate to single Postgres: db_bb -> schema 'bb' on db container
- Remove db_bb service, bb-network, db_bb volume from compose
- Remove api_tp targets from Makefile
- Clean up old migrate.go

main_dc/BB/api_bb/go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/go-chi/chi/v5 v5.2.3
 	github.com/go-chi/cors v1.2.2
 	github.com/golang-jwt/jwt/v5 v5.3.0
+	github.com/golang-migrate/migrate/v4 v4.18.2
 	golang.org/x/crypto v0.43.0
 	gorm.io/driver/postgres v1.6.0
 	gorm.io/gorm v1.31.0
@@ -15,8 +16,12 @@ require (
 	github.com/gabriel-vasile/mimetype v1.4.10 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
+	github.com/hashicorp/errwrap v1.1.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/leodido/go-urn v1.4.0 // indirect
+	github.com/lib/pq v1.10.9 // indirect
 	github.com/stretchr/testify v1.11.1 // indirect
+	go.uber.org/atomic v1.11.0 // indirect
 	go.uber.org/multierr v1.10.0 // indirect
 	golang.org/x/sys v0.37.0 // indirect
 )