refactor(backend): refactor project, add database migrations support

backend/app/core/db.py

@@ -0,0 +1,35 @@
+import os
+from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker
+from app.core.base import Base  # Import Base z nového souboru
+
+DATABASE_URL = os.getenv("DATABASE_URL")
+if not DATABASE_URL:
+    mariadb_host = os.getenv("MARIADB_HOST", "localhost")
+    mariadb_port = os.getenv("MARIADB_PORT", "3306")
+    mariadb_db = os.getenv("MARIADB_DB", "group_project")
+    mariadb_user = os.getenv("MARIADB_USER", "root")
+    mariadb_password = os.getenv("MARIADB_PASSWORD", "strongpassword")
+    if mariadb_host and mariadb_db and mariadb_user and mariadb_password:
+        DATABASE_URL = f"mysql+asyncmy://{mariadb_user}:{mariadb_password}@{mariadb_host}:{mariadb_port}/{mariadb_db}"
+    else:
+        raise Exception("Only MariaDB is supported. Please set the DATABASE_URL environment variable.")
+
+# Explicitní import všech modelů, aby byly registrovány v Base.metadata
+from app.models.user import User
+from app.models.transaction import Transaction
+
+from app.models.user import User
+
+# Pokud máš další modely, importuj je zde:
+# from app.models.other_model import OtherModel
+
+ssl_enabled = os.getenv("MARIADB_HOST", "localhost") != "localhost"
+connect_args = {"ssl": {"ssl": True}} if ssl_enabled else {}
+
+engine = create_async_engine(
+    DATABASE_URL,
+    pool_pre_ping=True,
+    echo=os.getenv("SQL_ECHO", "0") == "1",
+    connect_args=connect_args,
+)
+async_session_maker = async_sessionmaker(engine, expire_on_commit=False)