feat: add LocaleProvider and hooks for managing locale and timezone settings

src/components/LocaleProvider.tsx

@@ -0,0 +1,70 @@
+import { type Locale, LocaleProviderContext } from '@/contexts/LocaleContext'
+import { getSupportedTimezones } from '@/lib/utils/locale'
+import { useEffect, useState } from 'react'
+
+type LocaleProviderProps = {
+  children: React.ReactNode
+  defaultLocale?: Locale
+  defaultTimezone?: string
+  localeStorageKey?: string
+  timezoneStorageKey?: string
+}
+
+export function LocaleProvider({
+  children,
+  defaultLocale = 'fr-FR',
+  defaultTimezone = 'Europe/Paris',
+  localeStorageKey = 'locale',
+  timezoneStorageKey = 'timezone',
+  ...props
+}: LocaleProviderProps) {
+  const [locale, setLocaleState] = useState<Locale>(() => {
+    const stored = localStorage.getItem(localeStorageKey) as Locale
+    const validLocale = stored && ['en-US', 'fr-FR'].includes(stored) ? stored : defaultLocale
+    
+    // Set default in localStorage if not present
+    if (!stored) {
+      localStorage.setItem(localeStorageKey, defaultLocale)
+    }
+    
+    return validLocale
+  })
+
+  const [timezone, setTimezoneState] = useState<string>(() => {
+    const stored = localStorage.getItem(timezoneStorageKey)
+    const supportedTimezones = getSupportedTimezones()
+    const validTimezone = stored && supportedTimezones.includes(stored) ? stored : defaultTimezone
+    
+    // Set default in localStorage if not present
+    if (!stored) {
+      localStorage.setItem(timezoneStorageKey, defaultTimezone)
+    }
+    
+    return validTimezone
+  })
+
+  useEffect(() => {
+    // Set document language attribute for accessibility
+    document.documentElement.lang = locale.split('-')[0]
+  }, [locale])
+
+  const value = {
+    locale,
+    timezone,
+    setLocale: (newLocale: Locale) => {
+      localStorage.setItem(localeStorageKey, newLocale)
+      setLocaleState(newLocale)
+    },
+    setTimezone: (newTimezone: string) => {
+      localStorage.setItem(timezoneStorageKey, newTimezone)
+      setTimezoneState(newTimezone)
+    },
+  }
+
+  return (
+    <LocaleProviderContext.Provider {...props} value={value}>
+      {children}
+    </LocaleProviderContext.Provider>
+  )
+}
+