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/app/(main)/teams/TeamsAddButton.tsx

@@ -1,7 +1,6 @@
 import { Button, Dialog, DialogTrigger, Icon, Modal, Text, useToast } from '@umami/react-zen';
 import { useMessages, useModified } from '@/components/hooks';
 import { Plus } from '@/components/icons';
-import { messages } from '@/components/messages';
 import { TeamAddForm } from './TeamAddForm';
 
 export function TeamsAddButton({
@@ -11,12 +10,12 @@ export function TeamsAddButton({
   onSave?: () => void;
   isAdmin?: boolean;
 }) {
-  const { formatMessage, labels } = useMessages();
+  const { t, labels, messages } = useMessages();
   const { toast } = useToast();
   const { touch } = useModified();
 
   const handleSave = async () => {
-    toast(formatMessage(messages.saved));
+    toast(t(messages.saved));
     touch('teams');
     onSave?.();
   };
@@ -27,10 +26,10 @@ export function TeamsAddButton({
         <Icon>
           <Plus />
         </Icon>
-        <Text>{formatMessage(labels.createTeam)}</Text>
+        <Text>{t(labels.createTeam)}</Text>
       </Button>
       <Modal>
-        <Dialog title={formatMessage(labels.createTeam)} style={{ width: 400 }}>
+        <Dialog title={t(labels.createTeam)} style={{ width: 400 }}>
           {({ close }) => <TeamAddForm onSave={handleSave} onClose={close} isAdmin={isAdmin} />}
         </Dialog>
       </Modal>