don't edit a chat message while a reply streams

The edit button stayed active while a reply streamed. `submitConversation` returns early while loading, but the message bubble still closed its editor, so the edit was silently lost. The edit button is hidden while a reply streams, and an editor that's already open keeps its draft with send disabled until the reply ends.

web/src/components/chat/ChatMessage.tsx

@@ -133,7 +133,7 @@ export function MessageBubble({
             variant="select"
             size="icon"
             className="size-9 rounded-full"
-            disabled={!draftContent.trim()}
+            disabled={!draftContent.trim() || onEditSubmit == null}
             onClick={handleEditSubmit}
             aria-label={t("send")}
           >

web/src/pages/Chat.tsx

@@ -362,7 +362,7 @@ export default function ChatPage() {
             role="user"
             content={msg.content}
             messageIndex={i}
-            onEditSubmit={handleEditSubmit}
+            onEditSubmit={isLoading ? undefined : handleEditSubmit}
             isComplete
             showStats={showStats}
           />