feat(i18n): complete French locale and add common.changeLanguage

- Added `common.changeLanguage` key to `en.json`, `fr.json`, and `zh.json`.
- Updated `LanguageSelector.jsx` to use the new shared key.
- Completed `fr.json` with all keys from `en.json` and `zh.json`.
- Added translations for `closeSidebar`, `pricing`, and `language`.

web/src/components/layout/headerbar/LanguageSelector.jsx

@@ -54,7 +54,7 @@ const LanguageSelector = ({ currentLang, onLanguageChange, t }) => {
     >
       <Button
         icon={<Languages size={18} />}
-        aria-label={t('切换语言')}
+        aria-label={t('common.changeLanguage')}
         theme='borderless'
         type='tertiary'
         className='!p-1.5 !text-current focus:!bg-semi-color-fill-1 dark:focus:!bg-gray-700 !rounded-full !bg-semi-color-fill-0 dark:!bg-semi-color-fill-1 hover:!bg-semi-color-fill-1 dark:hover:!bg-semi-color-fill-2'