Feat/logger support log level validation0222 (#23436)

* 1、环境变量**：新增 `OPENCLAW_LOG_LEVEL`，可取值 `silent|fatal|error|warn|info|debug|trace`。设置后同时覆盖**文件日志**与**控制台**的级别，优先级高于配置文件。
2、启动参数**：在 `openclaw gateway run` 上新增 `--log-level <level>`，对该次进程同时生效于文件与控制台；未传时仍使用环境变量或配置文件。

* fix(logging): make log-level override global and precedence-safe

---------

Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/cli/log-level-option.ts

@@ -0,0 +1,12 @@
+import { InvalidArgumentError } from "commander";
+import { ALLOWED_LOG_LEVELS, type LogLevel, tryParseLogLevel } from "../logging/levels.js";
+
+export const CLI_LOG_LEVEL_VALUES = ALLOWED_LOG_LEVELS.join("|");
+
+export function parseCliLogLevelOption(value: string): LogLevel {
+  const parsed = tryParseLogLevel(value);
+  if (!parsed) {
+    throw new InvalidArgumentError(`Invalid --log-level (use ${CLI_LOG_LEVEL_VALUES})`);
+  }
+  return parsed;
+}