fix: 修复前后端启动问题，添加 BACKEND_PORT 配置

scripts/start.sh

@@ -28,6 +28,11 @@ check_config() {
     echo -e "${BLUE}📋 开始环境配置检查...${NC}"
     echo ""
     
+    # 加载 .env 文件
+    set -a
+    source "$PROJECT_DIR/.env" 2>/dev/null || true
+    set +a
+    
     PASS=0
     FAIL=0
     WARN=0
@@ -286,7 +291,7 @@ start_embedding() {
 # 启动 Python 服务
 # =============================================================================
 start_backend() {
-    echo -e "\n${BLUE}🚀 启动后端服务 (端口 8083)...${NC}"
+    echo -e "\n${BLUE}🚀 启动后端服务 (端口 8079)...${NC}"
     cd "$PROJECT_DIR"
     
     # 加载 .env 文件中的环境变量
@@ -294,9 +299,8 @@ start_backend() {
     source .env 2>/dev/null || true
     set +a
     
-    export PYTHONPATH="$PROJECT_DIR:$PROJECT_DIR/backend"
-    export BACKEND_PORT=8079
-    python backend/app/backend.py &
+    export PYTHONPATH="$PROJECT_DIR/backend"
+    python -m app.backend &
     BACKEND_PID=$!
     echo -e "${GREEN}✓ 后端服务已启动 (PID: $BACKEND_PID)${NC}"
     sleep 2
@@ -311,8 +315,8 @@ start_frontend() {
     source .env 2>/dev/null || true
     set +a
     
-    export PYTHONPATH="$PROJECT_DIR:$PROJECT_DIR/backend"
-    streamlit run frontend/src/frontend_main.py &
+    export PYTHONPATH="$PROJECT_DIR/frontend/src"
+    streamlit run frontend/src/frontend_main.py --server.port 8501 --server.address 0.0.0.0 &
     FRONTEND_PID=$!
     echo -e "${GREEN}✓ 前端服务已启动 (PID: $FRONTEND_PID)${NC}"
     echo -e "${GREEN}✓ 访问地址:${NC}"