Add chat settings modal & reply previews

Introduce a full ChatSettingsModal component for managing group chats (rename/icon upload, add/remove members, toggle moderators, leave/delete) and wire it into ChatRoomPage with a settings button. Add reply preview support end-to-end: new ReplyToSerializer and members_detail in backend serializers, updated frontend Message model (reply_to now contains preview object), and UI changes to Message to render reply excerpts. Improve socket handling to attach reply previews when available. Tweak backend Dockerfile to optionally install Windows/corporate CA bundle only if present and move pip install after copying source. Add Czech translations and small tooling/.claude config enhancements.

frontend/src/pages/social/chat/ChatRoomPage.tsx

@@ -2,6 +2,7 @@ import { useCallback, useEffect, useRef, useState } from "react";
 import { useParams } from "react-router-dom";
 import { useTranslation } from "react-i18next";
 import { useQueryClient } from "@tanstack/react-query";
+import { FiMoreVertical } from "react-icons/fi";
 import type { Message as MessageModel } from "@/api/generated/private/models/message";
 import { getApiSocialChatsListQueryKey, useApiSocialChatsRetrieve } from "@/api/generated/private/chat/chat";
 import { useAuth } from "@/hooks/useAuth";
@@ -11,6 +12,7 @@ import { useIntersectionLoader } from "@/hooks/useIntersectionLoader";
 import { messagesQueryKey, type CursorPaginated } from "@/api/social/feed";
 import Message from "@/components/social/chat/Message";
 import MessageComposer from "@/components/social/chat/MessageComposer";
+import ChatSettingsModal from "@/components/social/chat/ChatSettingsModal";
 import Spinner from "@/components/ui/Spinner";
 import EmptyState from "@/components/ui/EmptyState";
 import Avatar from "@/components/ui/Avatar";
@@ -33,6 +35,7 @@ export default function ChatRoomPage() {
 
   const [replyTo, setReplyTo] = useState<MessageModel | null>(null);
   const [typingUsers, setTypingUsers] = useState<string[]>([]);
+  const [settingsOpen, setSettingsOpen] = useState(false);
   const bottomRef = useRef<HTMLDivElement | null>(null);
 
   // Top sentinel triggers loading older messages (scroll-back).
@@ -85,11 +88,21 @@ export default function ChatRoomPage() {
   const handleSocketEvent = useCallback(
     (event: ChatSocketEvent) => {
       if (event.type === "new_chat_message" || event.type === "new_reply_chat_message") {
+        let replyTo: MessageModel["reply_to"] = null;
+        if (event.type === "new_reply_chat_message" && event.reply_to_id != null) {
+          const cached = queryClient.getQueryData<{ pages: CursorPaginated<MessageModel>[] }>(
+            messagesQueryKey(chatId),
+          );
+          const found = cached?.pages.flatMap((p) => p.results).find((m) => m.id === event.reply_to_id);
+          replyTo = found
+            ? { id: found.id, content: found.content, sender: found.sender }
+            : { id: event.reply_to_id, content: undefined, sender: { id: 0, username: "…", avatar: null } };
+        }
         appendMessage({
           id: event.message_id,
           chat: chatId,
           sender: { id: event.sender_id, username: event.sender, avatar: event.sender_avatar } as never,
-          reply_to: event.type === "new_reply_chat_message" ? event.reply_to_id : null,
+          reply_to: replyTo,
           content: event.message,
           is_edited: false,
           edited_at: null,
@@ -160,8 +173,24 @@ export default function ChatRoomPage() {
             </div>
           )}
         </div>
+        <button
+          type="button"
+          onClick={() => setSettingsOpen(true)}
+          className="inline-flex h-8 w-8 shrink-0 items-center justify-center rounded-full text-brand-text/60 hover:bg-brand-lines/15 hover:text-brand-text transition-colors"
+          aria-label={t("chat.settings.title")}
+        >
+          <FiMoreVertical size={17} />
+        </button>
       </header>
 
+      {chat && (
+        <ChatSettingsModal
+          chat={chat as Parameters<typeof ChatSettingsModal>[0]["chat"]}
+          open={settingsOpen}
+          onClose={() => setSettingsOpen(false)}
+        />
+      )}
+
       <div className="flex-1 overflow-y-auto py-2">
         {hasNextPage && (
           <div ref={topSentinelRef} className="flex justify-center py-2">