Add French localization

[Kyome22]

Context of Contribution

• Bug Fix
• Refactoring
• New Feature
• Others

Summary of the Proposal

Add French (fr) language support to RunCat365.

• Added RunCat365/Properties/Strings.fr.resx with all UI strings translated into French
• Added French to the SupportedLanguage enum in SupportedLanguage.cs
• Mapped ISO code "fr" to SupportedLanguage.French in GetCurrentLanguage()
• Added "fr-FR" culture in GetDefaultCultureInfo()
• Set font to "Consolas" (Latin-script) in GetFontName()
• Set IsFullWidth to false in IsFullWidth()

Reason for the new feature

French is one of the most widely spoken languages in the world, used natively across France, Belgium, Switzerland, Canada, and many other countries. Adding French support makes RunCat365 accessible to a large number of additional users.

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.

[Copilot]

Pull request overview

Adds French (fr) localization support to RunCat365 so the UI can automatically display French strings and use appropriate culture/font settings when the OS UI language is French.

Changes:

• Added SupportedLanguage.French with "fr" mapping and fr-FR default culture.
• Added Strings.fr.resx containing French translations for all existing UI string keys.
• Updated localization documentation and added a reusable “add-localization” skill doc.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
RunCat365/SupportedLanguage.cs	Adds French to the language enum and maps "fr" to culture/font/full-width behavior.
RunCat365/Properties/Strings.fr.resx	Provides French translations for the full set of existing localized string keys.
CLAUDE.md	Updates localization notes to reflect the new French resource file and maintenance expectations.
.claude/skills/add-localization/SKILL.md	Documents the standard process for adding future localizations (French used as example).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[mor39a]

The avaliable lenguages list was not updated in the Readme file.