Add Simplified Chinese language translation

[wcxu21]

Pull Request: Add Simplified Chinese language translation

Description

This pull request adds full Simplified Chinese (zh-CN) localization translation for the optimizerDuck application.

Covers all UI strings, setting descriptions, menu items, dialog prompts, tooltip texts, system feature labels, task scheduler messages, disk cleanup entries, startup manager, legal agreement pages, notification hints and every existing language resource entry.

The translation follows standard Windows terminology, keeps wording natural and consistent, fully preserves the original English meaning, and fits the existing UI layout perfectly. No content is omitted or mistranslated.

Type of Change

• 🌐 Translation/Localization update (i18n: or chore:)

Screenshots or Video (if applicable)

N/A – this is a pure localization resource update with no code or UI layout changes.

Additional Context

• This PR only adds translation XML files, no functional code changes.
• Fully compatible with the current app structure; Simplified Chinese can be selected directly in the language settings after merge.
• All string entries have been fully reviewed and proofread for accuracy, consistency and proper formatting.
• No side effects, registry changes or runtime behavior changes are introduced.

[itsfatduck]

Thanks for contributing the zh-CN localization support for optimizerDuck.
The PR looks well organized and complete. Approved!