refactor(mobile): conversation detail uses ownUserId + drops senderDeviceId

apps/mobile/app/(app)/conversations/[id].tsx

@@ -30,7 +30,7 @@ import { colors } from '../../../theme/colors';
 
 export default function ConversationDetail() {
   const { id } = useLocalSearchParams<{ id: string }>();
-  const { user, device, ownPrivateKey } = useAuth();
+  const { user, userId, ownPrivateKey } = useAuth();
   const { state: callState, startCall } = useCall();
   const router = useRouter();
 
@@ -54,7 +54,7 @@ export default function ConversationDetail() {
   const listRef = useRef<FlatList<DecryptedMessage>>(null);
 
   const load = useCallback(async () => {
-    if (!id || !device || !ownPrivateKey) return;
+    if (!id || !userId || !ownPrivateKey) return;
     setError(null);
     try {
       const all = await chat.listConversations(supabase);
@@ -63,7 +63,7 @@ export default function ConversationDetail() {
       const decrypted = await chat.decryptMessages({
         client: supabase,
         messages: ciphers,
-        ownDeviceId: device.id,
+        ownUserId: userId,
         ownPrivateKey,
       });
       setMessages(decrypted);
@@ -81,7 +81,7 @@ export default function ConversationDetail() {
     } catch (err: unknown) {
       setError(err instanceof Error ? err.message : 'Nachrichten konnten nicht geladen werden');
     }
-  }, [id, device, ownPrivateKey]);
+  }, [id, userId, ownPrivateKey]);
 
   useEffect(() => {
     void load();
@@ -103,7 +103,7 @@ export default function ConversationDetail() {
       : (conversation?.peer?.displayName ?? '…');
 
   async function handleSendText() {
-    if (!text.trim() || !user || !device || !ownPrivateKey || !id || sending) return;
+    if (!text.trim() || !user || !ownPrivateKey || !id || sending) return;
     setSending(true);
     setError(null);
     const replyToId = replyTo?.id;
@@ -113,7 +113,6 @@ export default function ConversationDetail() {
         conversationId: id,
         plaintext: text.trim(),
         senderUserId: user.id,
-        senderDeviceId: device.id,
         senderPrivateKey: ownPrivateKey,
         ...(replyToId ? { replyToId } : {}),
       });
@@ -128,7 +127,7 @@ export default function ConversationDetail() {
   }
 
   async function sendImage(pick: PickedImage) {
-    if (!user || !device || !ownPrivateKey || !id) return;
+    if (!user || !ownPrivateKey || !id) return;
     setSending(true);
     setError(null);
     try {
@@ -148,7 +147,6 @@ export default function ConversationDetail() {
         conversationId: id,
         plaintext: '',
         senderUserId: user.id,
-        senderDeviceId: device.id,
         senderPrivateKey: ownPrivateKey,
         attachmentHandles: [result.handle],
       });
@@ -300,7 +298,6 @@ export default function ConversationDetail() {
                 })}
                 reactions={reactions.get(item.id) ?? []}
                 myUserId={user?.id ?? null}
-                ownDeviceId={device?.id ?? null}
                 ownPrivateKey={ownPrivateKey}
                 onLongPress={() => setActiveMessage(item)}
                 onToggleReaction={(emoji) => {