feat: Add French locale support

[O2sa]

French is one of the most widely spoken languages globally. Adding French locale support will expand the application's accessibility to French-speaking developers and increase international reach.

Overview

French will be added as a new supported locale with the language code fr. Unlike Arabic and Persian, French uses left-to-right (LTR) layout, making this a straightforward addition.

Tasks

• Create a new locale file locales/fr.json with all translation keys from locales/en.json translated to French.
• Update lib/i18n-core.ts to add fr to the supportedLocales array.
• Add French entry to the localeMeta object in lib/i18n-core.ts with the following configuration:

  fr: { dir: "ltr", label: "Français" }

• Test the language switcher to ensure French appears in the dropdown menu.
• Test the application with French locale selected to ensure all UI elements display correctly.
• Verify that all text content renders properly without layout issues.
• Update CONTRIBUTING.md with instructions for translating content to French (if not already documented in the localization guide).

Translation Keys

All translation keys from the existing English locale must be translated to French. The keys include:

• Application titles and subtitles
• Error messages
• UI labels and buttons
• Explanations and descriptions
• Comparison metrics
• Community contribution labels
• And more (reference locales/en.json for the complete list)

Testing

• Language switcher displays "Français" correctly.
• All pages render without errors when French is selected.
• No layout shifts or broken styling in LTR mode.
• All French translations are grammatically correct and contextually appropriate.

Tip

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