Add Simplified Chinese localization

[wcxu21]

Context of Contribution

• Bug Fix
• Refactoring
• New Feature
• Others

Summary of the Proposal

Adds Simplified Chinese (zh-CN) as a supported language. This includes a new Strings.zh-CN.resx resource file with all translated strings, updates to SupportedLanguage.cs to include the new language enum, and modifications to the font switching logic to ensure proper rendering of Chinese characters (e.g., mapping to "Microsoft YaHei" or "Noto Sans SC").

Reason for the new feature

Simplified Chinese is one of the most widely spoken languages globally, representing a massive user base in China and Chinese communities worldwide. Adding this localization is critical for market accessibility and significantly improves the user experience for millions of potential users who prefer or require their system interface in their native language. The benefits of reaching this large audience far outweigh the minimal maintenance cost, as the implementation strictly follows the existing localization pattern used for other languages like German and French.

Checklist

• This PR does not contain commits of multiple contexts.
• Code follows proper indentation and naming conventions.
• Implemented using only APIs that can be submitted to the Microsoft Store.
• Works correctly in both dark theme and light theme.
• Works correctly on any device.

[Kyome22]

@wcxu21 Thank you for your contribution to this project.
In order for us to conduct the review through the correct process, please update your PR to align with the Pull Request Template.
https://github.com/Kyome22/RunCat365/blob/main/.github/pull_request_template.md

Additionally, if you are adding support for a new language, simply adding "Strings.zh-CN.resx" is not enough. There are other files that need to be edited as well. Please refer to the following "SKILL" section for more details.
https://github.com/Kyome22/RunCat365/blob/main/.claude/skills/add-localization/SKILL.md

[wcxu21]

@wcxu21 Thank you for your contribution to this project. In order for us to conduct the review through the correct process, please update your PR to align with the Pull Request Template. https://github.com/Kyome22/RunCat365/blob/main/.github/pull_request_template.md

Additionally, if you are adding support for a new language, simply adding "Strings.zh-CN.resx" is not enough. There are other files that need to be edited as well. Please refer to the following "SKILL" section for more details. https://github.com/Kyome22/RunCat365/blob/main/.claude/skills/add-localization/SKILL.md

Thank you for your suggestion. I have re-added and revised the relevant language support files. You can check if it's correct. If you have any further questions, please let me know. Thank you for your work.

[Copilot]

Pull request overview

Adds Simplified Chinese (zh-CN) localization support to RunCat365, including language detection, culture/font defaults, and a new translated strings resource.

Changes:

• Added Chinese to SupportedLanguage and mapped it to zh-CN culture defaults and a Chinese-capable font.
• Introduced Strings.zh-CN.resx with Simplified Chinese translations for the app UI.
• Updated localization documentation to list the new resource file and font choice.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
RunCat365/SupportedLanguage.cs	Adds a new language enum value plus culture/font mappings for Chinese.
RunCat365/Properties/Strings.zh-CN.resx	New Simplified Chinese string resources.
CLAUDE.md	Documents the new zh-CN resource and font choice in localization notes.

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[Kyome22]

Thank you so much for contributing the Simplified Chinese translations!
I will check for any functional issues and make adjustments before the release.
(We might wait to release everything at once after we've finished supporting Traditional Chinese and other languages.)