feat(core): clear saved chat and add message deletion scopes

backend:

- add message_hidden table for per-user message hiding

- support DELETE /messages/{id}?for_all=true|false

- implement delete-for-me vs delete-for-all logic by chat type/permissions

- add POST /chats/{chat_id}/clear and route saved chat deletion to clear

web:

- saved messages action changed from delete to clear

- message context menu now supports delete modal: for me / for everyone

- add local store helpers removeMessage/clearChatMessages

- include realtime stability improvements and app error boundary

web/src/components/MessageList.tsx

@@ -1,6 +1,6 @@
-import { useMemo, useState } from "react";
+import { useEffect, useMemo, useState } from "react";
 import { createPortal } from "react-dom";
-import { forwardMessage, pinMessage } from "../api/chats";
+import { deleteMessage, forwardMessage, pinMessage } from "../api/chats";
 import { useAuthStore } from "../store/authStore";
 import { useChatStore } from "../store/chatStore";
 import { formatTime } from "../utils/format";
@@ -19,11 +19,14 @@ export function MessageList() {
   const chats = useChatStore((s) => s.chats);
   const setReplyToMessage = useChatStore((s) => s.setReplyToMessage);
   const updateChatPinnedMessage = useChatStore((s) => s.updateChatPinnedMessage);
+  const removeMessage = useChatStore((s) => s.removeMessage);
   const [ctx, setCtx] = useState<ContextMenuState>(null);
   const [forwardMessageId, setForwardMessageId] = useState<number | null>(null);
   const [forwardQuery, setForwardQuery] = useState("");
   const [forwardError, setForwardError] = useState<string | null>(null);
   const [isForwarding, setIsForwarding] = useState(false);
+  const [deleteMessageId, setDeleteMessageId] = useState<number | null>(null);
+  const [deleteError, setDeleteError] = useState<string | null>(null);
 
   const messages = useMemo(() => {
     if (!activeChatId) {
@@ -44,6 +47,19 @@ export function MessageList() {
     });
   }, [chats, forwardQuery]);
 
+  useEffect(() => {
+    const onKeyDown = (event: KeyboardEvent) => {
+      if (event.key !== "Escape") {
+        return;
+      }
+      setCtx(null);
+      setForwardMessageId(null);
+      setDeleteMessageId(null);
+    };
+    window.addEventListener("keydown", onKeyDown);
+    return () => window.removeEventListener("keydown", onKeyDown);
+  }, []);
+
   if (!activeChatId) {
     return <div className="flex h-full items-center justify-center text-slate-300/80">Select a chat</div>;
   }
@@ -72,6 +88,20 @@ export function MessageList() {
     setCtx(null);
   }
 
+  async function handleDelete(forAll: boolean) {
+    if (!deleteMessageId) {
+      return;
+    }
+    try {
+      await deleteMessage(deleteMessageId, forAll);
+      removeMessage(chatId, deleteMessageId);
+      setDeleteMessageId(null);
+      setDeleteError(null);
+    } catch {
+      setDeleteError("Failed to delete message");
+    }
+  }
+
   return (
     <div className="flex h-full flex-col" onClick={() => setCtx(null)}>
       {activeChat?.pinned_message_id ? (
@@ -148,6 +178,16 @@ export function MessageList() {
             >
               Forward
             </button>
+            <button
+              className="block w-full rounded px-2 py-1.5 text-left text-sm text-red-300 hover:bg-slate-800"
+              onClick={() => {
+                setDeleteMessageId(ctx.messageId);
+                setDeleteError(null);
+                setCtx(null);
+              }}
+            >
+              Delete
+            </button>
             <button className="block w-full rounded px-2 py-1.5 text-left text-sm hover:bg-slate-800" onClick={() => void handlePin(ctx.messageId)}>
               Pin / Unpin
             </button>
@@ -187,6 +227,29 @@ export function MessageList() {
           </div>
         </div>
       ) : null}
+
+      {deleteMessageId ? (
+        <div className="absolute inset-0 z-50 flex items-end justify-center bg-slate-950/55 p-3" onClick={() => setDeleteMessageId(null)}>
+          <div className="w-full rounded-xl border border-slate-700/80 bg-slate-900 p-3" onClick={(e) => e.stopPropagation()}>
+            <p className="mb-2 text-sm font-semibold">Delete message</p>
+            <p className="mb-3 text-xs text-slate-400">Choose how to delete this message.</p>
+            <div className="space-y-2">
+              <button className="w-full rounded bg-red-500 px-3 py-2 text-sm font-semibold text-white" onClick={() => void handleDelete(false)}>
+                Delete for me
+              </button>
+              {canDeleteForEveryone(messagesMap.get(deleteMessageId), activeChat, me?.id) ? (
+                <button className="w-full rounded bg-red-600 px-3 py-2 text-sm font-semibold text-white" onClick={() => void handleDelete(true)}>
+                  Delete for everyone
+                </button>
+              ) : null}
+              <button className="w-full rounded bg-slate-700 px-3 py-2 text-sm" onClick={() => setDeleteMessageId(null)}>
+                Cancel
+              </button>
+            </div>
+            {deleteError ? <p className="mt-2 text-xs text-red-400">{deleteError}</p> : null}
+          </div>
+        </div>
+      ) : null}
     </div>
   );
 }
@@ -231,3 +294,14 @@ function chatLabel(chat: { display_title?: string | null; title: string | null;
   if (chat.type === "group") return "Group";
   return "Channel";
 }
+
+function canDeleteForEveryone(
+  message: { sender_id: number } | undefined,
+  chat: { type: "private" | "group" | "channel"; is_saved?: boolean } | undefined,
+  meId: number | undefined
+): boolean {
+  if (!message || !chat || !meId) return false;
+  if (chat.is_saved) return false;
+  if (chat.type === "private") return true;
+  return message.sender_id === meId;
+}