chore(docker): Refactor sandbox state management and improve Docker integration (#1068)

* Refactor sandbox state management and improve Docker integration

- Removed FileSandboxStateStore and SandboxStateStore classes for a cleaner architecture.
- Enhanced LocalContainerBackend to handle port allocation retries and introduced environment variable support for sandbox host configuration.
- Updated Paths class to include host_base_dir for Docker volume mounts and ensured proper permissions for sandbox directories.
- Modified ExtensionsConfig to improve error handling when loading configuration files and adjusted environment variable resolution.
- Updated sandbox configuration to include a replicas option for managing concurrent sandbox containers.
- Improved logging and context management in SandboxMiddleware for better sandbox lifecycle handling.
- Enhanced network port allocation logic to bind to 0.0.0.0 for compatibility with Docker.
- Updated Docker Compose files to ensure proper volume management and environment variable configuration.
- Created scripts to ensure necessary configuration files are present before starting services.
- Cleaned up unused MCP server configurations in extensions_config.example.json.

* Address Copilot review suggestions from PR #1068 (#9)

---------

Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com>

scripts/docker.sh

@@ -125,6 +125,39 @@ start() {
         echo ""
     fi
     
+    # Ensure config.yaml exists before starting.
+    if [ ! -f "$PROJECT_ROOT/config.yaml" ]; then
+        if [ -f "$PROJECT_ROOT/config.example.yaml" ]; then
+            cp "$PROJECT_ROOT/config.example.yaml" "$PROJECT_ROOT/config.yaml"
+            echo ""
+            echo -e "${YELLOW}============================================================${NC}"
+            echo -e "${YELLOW}  config.yaml has been created from config.example.yaml.${NC}"
+            echo -e "${YELLOW}  Please edit config.yaml to set your API keys and model   ${NC}"
+            echo -e "${YELLOW}  configuration before starting DeerFlow.                  ${NC}"
+            echo -e "${YELLOW}============================================================${NC}"
+            echo ""
+            echo -e "${YELLOW}  Edit the file:  $PROJECT_ROOT/config.yaml${NC}"
+            echo -e "${YELLOW}  Then run:        make docker-start${NC}"
+            echo ""
+            exit 0
+        else
+            echo -e "${YELLOW}✗ config.yaml not found and no config.example.yaml to copy from.${NC}"
+            exit 1
+        fi
+    fi
+
+    # Ensure extensions_config.json exists as a file before mounting.
+    # Docker creates a directory when bind-mounting a non-existent host path.
+    if [ ! -f "$PROJECT_ROOT/extensions_config.json" ]; then
+        if [ -f "$PROJECT_ROOT/extensions_config.example.json" ]; then
+            cp "$PROJECT_ROOT/extensions_config.example.json" "$PROJECT_ROOT/extensions_config.json"
+            echo -e "${BLUE}Created extensions_config.json from example${NC}"
+        else
+            echo "{}" > "$PROJECT_ROOT/extensions_config.json"
+            echo -e "${BLUE}Created empty extensions_config.json${NC}"
+        fi
+    fi
+
     echo "Building and starting containers..."
     cd "$DOCKER_DIR" && $COMPOSE_CMD up --build -d --remove-orphans $services
     echo ""
@@ -177,8 +210,15 @@ logs() {
 
 # Stop Docker development environment
 stop() {
+    # DEER_FLOW_ROOT is referenced in docker-compose-dev.yaml; set it before
+    # running compose down to suppress "variable is not set" warnings.
+    if [ -z "$DEER_FLOW_ROOT" ]; then
+        export DEER_FLOW_ROOT="$PROJECT_ROOT"
+    fi
     echo "Stopping Docker development services..."
     cd "$DOCKER_DIR" && $COMPOSE_CMD down
+    echo "Cleaning up sandbox containers..."
+    "$SCRIPT_DIR/cleanup-containers.sh" deer-flow-sandbox 2>/dev/null || true
     echo -e "${GREEN}✓ Docker services stopped${NC}"
 }