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/grpc.go

@@ -0,0 +1,17 @@
+package config
+
+import "fmt"
+
+// GRPCConfig gRPC 服务器配置
+type GRPCConfig struct {
+	Enabled     bool   `mapstructure:"enabled"`
+	Port        int    `mapstructure:"port"`
+	TLSEnabled  bool   `mapstructure:"tls_enabled"`
+	TLSCertFile string `mapstructure:"tls_cert_file"`
+	TLSKeyFile  string `mapstructure:"tls_key_file"`
+}
+
+// Address 返回 gRPC 服务器监听地址
+func (c *GRPCConfig) Address() string {
+	return fmt.Sprintf(":%d", c.Port)
+}