refactor: update alembic migrations and import models

- Added import for `alta_log_models` to `env.py` for autogeneration of tables outside of `models.py`.
- Deleted several obsolete migration files, including those related to classification descriptions, initial data seeding, and legacy fields in the company certification schema.
- Cleaned up migration history by removing unused migration scripts to streamline future updates.

backend/alembic/env.py

@@ -300,6 +300,9 @@ def import_models_from_dir(dir_path: str):
 modules_dir = os.path.join(BASE_DIR, "api", "v1", "modules")
 import_models_from_dir(modules_dir)
 
+# Tablas declaradas fuera de models.py / carpeta models/ (autogenerate)
+import api.v1.modules.a76.general_catalogs.doda.alta_log_models  # noqa: F401
+
 
 def run_migrations_offline() -> None:
     """Run migrations in 'offline' mode.