feat(social): show friend presence and require online listening

apps/mobile/src/features/social/Social.tsx

@@ -123,6 +123,7 @@ export function SocialScreen({ root = false }: { root?: boolean }) {
       {!people.length && inbox.data && !results.isFetching && <Muted>{t(q.length >= 2 ? 'social.no_results' : 'social.empty')}</Muted>}
       {people.map(p => <View key={p.id} style={{ padding: 16, borderRadius: 16, backgroundColor: colors.surface, gap: 10 }}>
         <Text style={{ color: colors.text, fontWeight: '600', fontSize: 17 }}>{p.display_name}</Text><Muted>@{p.username} · {t(`social.rel_${p.relationship}`)}</Muted>
+        {p.relationship === 'friend' && <Text style={{ color: colors.text2, fontSize: 12 }}>{t(p.online ? 'social.online' : 'social.offline')}</Text>}
         {p.activity && <View style={{ borderLeftWidth: 2, borderLeftColor: colors.ok, paddingLeft: 12, gap: 6 }}>
           <Text style={{ color: colors.ok, fontSize: 12 }}>{t('social.listening')}</Text>
           <Pressable accessibilityRole="link" onPress={() => router.push({ pathname: '/social-track', params: { id: p.activity!.track_id } })}><Text style={{ color: colors.accent2 }}>{p.activity.track_title}</Text></Pressable>