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

configs/config.yaml

@@ -190,3 +190,14 @@ conversation_cache:
   batch_threshold: 100     # 条数阈值
   batch_max_size: 500      # 单次最大批量
   buffer_max_size: 10000   # 写缓冲最大条数
+
+# gRPC 服务器配置
+# 环境变量:
+#   APP_GRPC_ENABLED, APP_GRPC_PORT
+#   APP_GRPC_TLS_ENABLED, APP_GRPC_TLS_CERT_FILE, APP_GRPC_TLS_KEY_FILE
+grpc:
+  enabled: true
+  port: 50051
+  tls_enabled: false
+  tls_cert_file: ""
+  tls_key_file: ""