feat: 添加 SQLAlchemy 模型 + Alembic 数据库迁移

alembic/env.py

@@ -0,0 +1,34 @@
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+from app.models.announcement import Base
+
+config = context.config
+
+target_metadata = Base.metadata
+
+
+def run_migrations_offline():
+    from app.config import settings
+    url = settings.database_url
+    context.configure(url=url, target_metadata=target_metadata, literal_binds=True)
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    from app.config import settings
+    connectable = engine_from_config(
+        {"sqlalchemy.url": settings.database_url},
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+    with connectable.connect() as connection:
+        context.configure(connection=connection, target_metadata=target_metadata)
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()