fix: editable decrypt + windows realtime wake (v0.7.1)

Edit message decrypt:
- handleUpdate in useConversationMessages now refetches the canonical row
  via REST after a realtime UPDATE instead of trusting the realtime
  payload's bytea encoding. Same pattern as handleInsert — base64 vs
  `\x…` hex serialisation varies across supabase/postgrest versions and
  was silently producing undecryptable ciphertext for edited messages
  on the receiver side

Windows WebView2 background throttling:
- ConversationsContext, useFriendships and useConversationMessages now
  listen for visibilitychange / focus / online events and trigger both a
  fresh REST refresh and a best-effort channel.subscribe() on wake.
  WebView2 aggressively throttles background WebSockets and was dropping
  realtime events entirely while the window was minimised, so new
  messages and friend acceptances only surfaced after a manual reload

Bump tauri version 0.7.0 -> 0.7.1

apps/desktop/src/lib/useFriendships.ts

@@ -44,7 +44,24 @@ export function useFriendships(userId: string | undefined): FriendshipsState & {
       })
       .subscribe();
 
+    // Windows WebView2 throttles background sockets — refresh on wake.
+    const onAwake = () => {
+      if (document.visibilityState !== 'visible') return;
+      void refresh();
+      try {
+        channel.subscribe();
+      } catch {
+        /* already live */
+      }
+    };
+    document.addEventListener('visibilitychange', onAwake);
+    window.addEventListener('focus', onAwake);
+    window.addEventListener('online', onAwake);
+
     return () => {
+      document.removeEventListener('visibilitychange', onAwake);
+      window.removeEventListener('focus', onAwake);
+      window.removeEventListener('online', onAwake);
       void supabase.removeChannel(channel);
     };
   }, [userId, refresh]);