Simplify i18n: remove old react-intl artifacts, rename formatMessage to t, replace FormattedMessage with t.rich().

- Rewrite messages.ts to plain string key maps (remove MessageDescriptor)
- Rewrite useMessages hook to expose t from useTranslations() directly
- Rename formatMessage → t across 193 consumer files
- Replace custom FormattedMessage component with next-intl t.rich()
- Update 52 language files to use rich text tags (<b>, <a>)
- Remove all direct imports from @/components/messages in favor of useMessages()

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/hooks/useFormat.ts

@@ -6,7 +6,7 @@ import { useLocale } from './useLocale';
 import { useMessages } from './useMessages';
 
 export function useFormat() {
-  const { formatMessage, labels } = useMessages();
+  const { t, labels } = useMessages();
   const { locale } = useLocale();
   const { countryNames } = useCountryNames(locale);
   const { languageNames } = useLanguageNames(locale);
@@ -20,7 +20,7 @@ export function useFormat() {
   };
 
   const formatDevice = (value: string): string => {
-    return formatMessage(labels[value] || labels.unknown);
+    return t(labels[value] || labels.unknown);
   };
 
   const formatCountry = (value: string): string => {