Feature Request: Add dreaming.language config option to memory-core plugin

Is your feature request related to a problem?

The memory-core plugin's Dreaming feature generates dream diary entries in memory/dreaming/{light,deep,rem}/ directories. However, the generated content uses English headings by default (e.g., "Light Sleep", "Deep Sleep", "REM Sleep", "Reflections", "No strong patterns surfaced"), even when the user's system language preference is Chinese.

Currently, there is no configuration option to specify the output language for dreaming. Each time the cron job runs, if English headings are generated, the user must manually translate them.

Describe the solution you'd like

Add a language option to the dreaming config section:

{
  "plugins": {
    "entries": {
      "memory-core": {
        "config": {
          "dreaming": {
            "enabled": true,
            "language": "zh-CN"
          }
        }
      }
    }
  }
}

This would make the subagent prompt generate all dreaming output (headings, labels, reflections) in the specified locale.

Expected behavior

When language: "zh-CN" is set:

Schema addition

plugins.entries.memory-core.config.dreaming.language
  type: string
  default: "en"
  placeholder: "zh-CN"
  help: "ISO 639-1 locale code for Dream Diary narrative subagent output (headings, labels, and generated text). Affects light/deep/rem phase outputs."

Describe alternatives you've considered

1. Manual translation: After each dreaming cron run, manually edit the generated files to translate headings and content. This is tedious and doesn't scale.

2. Post-processing script: Write a script to auto-translate dreaming files after generation. This is a workaround rather than a proper solution.

3. MEMORY.md language preference: While MEMORY.md already contains "所有日记、日志、记录必须使用中文书写", the dreaming subagent doesn't read MEMORY.md during its isolated cron execution.

Additional context

• OpenClaw version: 2026.5.7
• Plugin: @openclaw/memory-core
• Current config path: plugins.entries.memory-core.config.dreaming
• Affected cron: "Memory Dreaming Promotion" (runs daily at 03:00 Asia/Shanghai)
• User context: Chinese-speaking user with agents.defaults.userTimezone: "Asia/Shanghai"

This is a relatively small change: the dreaming subagent prompt just needs to receive the language preference and use it for all generated headings/labels/content.