feat(grpc): add gRPC server infrastructure and schedule sync service

Add gRPC server support with configurable TLS, environment-based settings, and Wire injection. Implement schedule synchronization service with task runner integration for external course data fetching.

- Add gRPC configuration with env var overrides (APP_GRPC_ENABLED, APP_GRPC_PORT, etc.)
- Create gRPC server infrastructure with runner task management
- Implement ScheduleSyncService for course data synchronization
- Add sync endpoint to schedule handler for external system integration
- Update repository with context-aware batch delete operation
- Wire all dependencies including zap logger for structured logging

internal/grpc/runner/server.go

@@ -0,0 +1,145 @@
+package runner
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"time"
+
+	"carrot_bbs/internal/config"
+	"carrot_bbs/proto/runner"
+
+	"go.uber.org/zap"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/credentials/insecure"
+)
+
+// Server gRPC 服务器
+type Server struct {
+	cfg     *config.GRPCConfig
+	logger  *zap.Logger
+	hub     *RunnerHub
+	grpcSrv *grpc.Server
+}
+
+// NewServer 创建新的 gRPC 服务器
+func NewServer(cfg *config.GRPCConfig, logger *zap.Logger) *Server {
+	// 创建 TaskManager 和 RunnerHub，解决循环依赖
+	taskManager := NewTaskManager(nil, 60*time.Second, logger)
+	hub := NewRunnerHub(taskManager, logger)
+	taskManager.SetHub(hub)
+
+	return &Server{
+		cfg:    cfg,
+		logger: logger,
+		hub:    hub,
+	}
+}
+
+// Start 启动 gRPC 服务器
+func (s *Server) Start() error {
+	if !s.cfg.Enabled {
+		s.logger.Info("gRPC server is disabled")
+		return nil
+	}
+
+	lis, err := net.Listen("tcp", s.cfg.Address())
+	if err != nil {
+		return fmt.Errorf("failed to listen on %s: %w", s.cfg.Address(), err)
+	}
+
+	// 配置 gRPC 服务器选项
+	var opts []grpc.ServerOption
+
+	// 配置 TLS
+	if s.cfg.TLSEnabled {
+		if s.cfg.TLSCertFile == "" || s.cfg.TLSKeyFile == "" {
+			return fmt.Errorf("TLS enabled but cert/key files not specified")
+		}
+		creds, err := credentials.NewServerTLSFromFile(s.cfg.TLSCertFile, s.cfg.TLSKeyFile)
+		if err != nil {
+			return fmt.Errorf("failed to load TLS credentials: %w", err)
+		}
+		opts = append(opts, grpc.Creds(creds))
+		s.logger.Info("gRPC server TLS enabled")
+	} else {
+		s.logger.Warn("gRPC server running without TLS")
+	}
+
+	s.grpcSrv = grpc.NewServer(opts...)
+	runner.RegisterRunnerHubServer(s.grpcSrv, s.hub)
+
+	s.logger.Info("gRPC server starting", zap.String("address", s.cfg.Address()))
+
+	go func() {
+		if err := s.grpcSrv.Serve(lis); err != nil {
+			s.logger.Error("gRPC server error", zap.Error(err))
+		}
+	}()
+
+	// 启动后台任务清理协程
+	go s.backgroundCleanup()
+
+	return nil
+}
+
+// backgroundCleanup 后台清理任务
+func (s *Server) backgroundCleanup() {
+	ticker := time.NewTicker(30 * time.Second)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		// 清理超时的 Runner 连接
+		s.hub.CheckStaleRunners(90 * time.Second)
+	}
+}
+
+// Stop 停止 gRPC 服务器
+func (s *Server) Stop() {
+	if s.grpcSrv != nil {
+		s.logger.Info("Stopping gRPC server")
+		s.grpcSrv.GracefulStop()
+	}
+}
+
+// GetHub 获取 RunnerHub
+func (s *Server) GetHub() *RunnerHub {
+	return s.hub
+}
+
+// GetTaskManager 获取 TaskManager
+func (s *Server) GetTaskManager() *TaskManager {
+	return s.hub.taskManager
+}
+
+// Shutdown 优雅关闭
+func (s *Server) Shutdown(ctx context.Context) error {
+	if s.grpcSrv == nil {
+		return nil
+	}
+
+	done := make(chan struct{})
+	go func() {
+		s.grpcSrv.GracefulStop()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		s.logger.Info("gRPC server stopped gracefully")
+		return nil
+	case <-ctx.Done():
+		s.logger.Warn("gRPC server shutdown timeout, forcing stop")
+		s.grpcSrv.Stop()
+		return ctx.Err()
+	}
+}
+
+// GetClientCredentials 获取客户端凭证配置
+func GetClientCredentials(cfg *config.GRPCConfig) (credentials.TransportCredentials, error) {
+	if cfg.TLSEnabled {
+		return credentials.NewClientTLSFromFile(cfg.TLSCertFile, "")
+	}
+	return insecure.NewCredentials(), nil
+}