refactor(desktop): AuthContext exposes userKeyState instead of device record

Replaces the per-device DeviceRecord lookup with a per-user discriminated
union (loading | needs-setup | needs-unlock | unlocked). Heartbeat block
deleted (telemetry no longer device-bound); webPush keyed by install-id.

apps/desktop/src/components/MessageBubble.tsx

@@ -10,6 +10,7 @@ import { createPortal } from 'react-dom';
 import { useTranslation } from 'react-i18next';
 
 import { useAuth } from '../context/AuthContext';
+import { ensureInstallId } from '../lib/installId';
 import { supabase } from '../lib/supabase';
 import { cachedUserKey } from '../lib/userIdentity';
 import type { AggregatedReaction } from '../lib/useMessageReactions';
@@ -97,7 +98,7 @@ export function MessageBubble({
   highlighted = false,
 }: Props) {
   const { t } = useTranslation(['app']);
-  const { session, device } = useAuth();
+  const { session } = useAuth();
 
   const parsed = parseMessagePayload(message.plaintext);
   const initialText = parsed.kind === 'text' ? parsed.text : '';
@@ -190,7 +191,7 @@ export function MessageBubble({
   }, [pickerOpen]);
 
   const handleEditSave = useCallback(async () => {
-    if (!session || !device) return;
+    if (!session) return;
     const trimmed = editText.trim();
     if (!trimmed || trimmed === bodyText) {
       setEditing(false);
@@ -208,7 +209,7 @@ export function MessageBubble({
         conversationId,
         newPlaintext: trimmed,
         senderUserId: session.user.id,
-        senderDeviceId: device.id,
+        senderDeviceId: ensureInstallId(),
         senderPrivateKey: priv,
       });
       setEditing(false);
@@ -224,7 +225,7 @@ export function MessageBubble({
     } finally {
       setBusy(false);
     }
-  }, [editText, message.id, message.plaintext, conversationId, session, device, t]);
+  }, [editText, message.id, message.plaintext, conversationId, session, t]);
 
   const handleDelete = useCallback(async () => {
     if (busy) return;