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/config/config.go

@@ -25,6 +25,7 @@ type Config struct {
 	OpenAI            OpenAIConfig            `mapstructure:"openai"`
 	Email             EmailConfig             `mapstructure:"email"`
 	ConversationCache ConversationCacheConfig `mapstructure:"conversation_cache"`
+	GRPC              GRPCConfig              `mapstructure:"grpc"`
 }
 
 // Load 加载配置文件
@@ -127,6 +128,12 @@ func Load(configPath string) (*Config, error) {
 	viper.SetDefault("conversation_cache.batch_threshold", 100)
 	viper.SetDefault("conversation_cache.batch_max_size", 500)
 	viper.SetDefault("conversation_cache.buffer_max_size", 10000)
+	// GRPC 默认值
+	viper.SetDefault("grpc.enabled", true)
+	viper.SetDefault("grpc.port", 50051)
+	viper.SetDefault("grpc.tls_enabled", false)
+	viper.SetDefault("grpc.tls_cert_file", "")
+	viper.SetDefault("grpc.tls_key_file", "")
 
 	if err := viper.ReadInConfig(); err != nil {
 		return nil, fmt.Errorf("failed to read config: %w", err)
@@ -202,6 +209,12 @@ func Load(configPath string) (*Config, error) {
 	cfg.Email.UseTLS, _ = strconv.ParseBool(getEnvOrDefault("APP_EMAIL_USE_TLS", fmt.Sprintf("%t", cfg.Email.UseTLS)))
 	cfg.Email.InsecureSkipVerify, _ = strconv.ParseBool(getEnvOrDefault("APP_EMAIL_INSECURE_SKIP_VERIFY", fmt.Sprintf("%t", cfg.Email.InsecureSkipVerify)))
 	cfg.Email.Timeout, _ = strconv.Atoi(getEnvOrDefault("APP_EMAIL_TIMEOUT", fmt.Sprintf("%d", cfg.Email.Timeout)))
+	// GRPC 环境变量覆盖
+	cfg.GRPC.Enabled, _ = strconv.ParseBool(getEnvOrDefault("APP_GRPC_ENABLED", fmt.Sprintf("%t", cfg.GRPC.Enabled)))
+	cfg.GRPC.Port, _ = strconv.Atoi(getEnvOrDefault("APP_GRPC_PORT", fmt.Sprintf("%d", cfg.GRPC.Port)))
+	cfg.GRPC.TLSEnabled, _ = strconv.ParseBool(getEnvOrDefault("APP_GRPC_TLS_ENABLED", fmt.Sprintf("%t", cfg.GRPC.TLSEnabled)))
+	cfg.GRPC.TLSCertFile = getEnvOrDefault("APP_GRPC_TLS_CERT_FILE", cfg.GRPC.TLSCertFile)
+	cfg.GRPC.TLSKeyFile = getEnvOrDefault("APP_GRPC_TLS_KEY_FILE", cfg.GRPC.TLSKeyFile)
 
 	return &cfg, nil
 }