fix: P3-1 unify database config with app.config

apps/api/app/core/database.py

@@ -1,34 +1,49 @@
-import os
-from typing import Optional
+"""Database session management and engine configuration.
 
-from pydantic_settings import BaseSettings, SettingsConfigDict
+统一使用 app.config 中的数据库配置，移除重复的 DatabaseSettings。
+"""
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, Session
+from contextlib import contextmanager
+from typing import Generator
+
+from app.config import settings
 
 
-class DatabaseSettings(BaseSettings):
-    database_url: str = "postgresql+psycopg://postgres:postgres@postgres:5432/xiaoxia_saas"
-    pool_size: int = 20
-    max_overflow: int = 40
-    pool_timeout: int = 30
-    pool_recycle: int = 3600
+engine = create_engine(
+    settings.database_url,
+    pool_size=settings.DATABASE_POOL_SIZE,
+    max_overflow=settings.DATABASE_MAX_OVERFLOW,
+    pool_timeout=settings.DATABASE_POOL_TIMEOUT,
+    pool_recycle=settings.DATABASE_POOL_RECYCLE,
+)
 
-    model_config = SettingsConfigDict(
-        env_file=".env",
-        env_file_encoding="utf-8",
-        case_sensitive=False,
-        extra="ignore",
-    )
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 
 
-_settings: Optional[DatabaseSettings] = None
+def get_db() -> Generator[Session, None, None]:
+    """Dependency for getting database sessions."""
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
 
 
-def get_database_settings() -> DatabaseSettings:
-    global _settings
-    if _settings is None:
-        env = os.getenv("APP_ENV", "development")
-        env_file = f".env.{env}" if env != "development" else ".env"
-        if os.path.exists(env_file):
-            _settings = DatabaseSettings(_env_file=env_file)
-        else:
-            _settings = DatabaseSettings()
-    return _settings
+@contextmanager
+def get_db_context() -> Generator[Session, None, None]:
+    """Context manager for database sessions.
+    
+    Usage:
+        with get_db_context() as db:
+            db.query(Model).all()
+    """
+    db = SessionLocal()
+    try:
+        yield db
+        db.commit()
+    except Exception:
+        db.rollback()
+        raise
+    finally:
+        db.close()