feat(openflare): migrate of_node_access_logs to ClickHouse

Move node access log storage from PostgreSQL/SQLite to ClickHouse
(database: openflare). System startup now requires a healthy ClickHouse
connection and auto-initializes the schema. Agent heartbeat writes access
logs via batch insert; goose migration drops the legacy relational table.

openflare-server/internal/model/errs.go

@@ -6,6 +6,7 @@ package model
 const (
 	errRegistrationDisabled                 = "注册已关闭"
 	errDatabaseNotInitialized               = "database not initialized"
+	errClickHouseNotInitialized             = "clickhouse not initialized"
 	errUsernameExists                       = "用户名已存在"
 	errEmailAlreadyBound                    = "该邮箱已被其他账号绑定"
 	errConfigIntParseFailed                 = "配置 %s 的值 '%s' 无法转换为整数: %w"