feat!: remove direct messaging (chat)

E2EE direct messages, the chat dock, the Messages module, the message
WebSocket and its realtime registry, and the messages / message_keys
tables (migration 0097; the downgrade restores the empty schema). Prod
held two welcome notes, no message between people and one key — never
used (owner decision, E34). WebSocket now has no owner module: the lint
bans it everywhere. Privacy policy updated: it no longer promises E2EE
for a feature that is gone.

frontend/src/components/modulePages.tsx

@@ -10,7 +10,6 @@ import { useSavedViews } from "./savedViewsContext";
 // that file exports only data and this one only components (Fast Refresh). Their lazy chunks are
 // exported alongside so the registry can attach each chunk's preload to the wrapper that renders it.
 export const Feed = lazyWithPreload(() => import("./Feed"));
-export const Messages = lazyWithPreload(() => import("./Messages"));
 
 // The GLOBAL feed page: wires <Feed> to the app-wide feed filters / view / live-search. (The channel
 // page renders <Feed> itself with its own channel-scoped filters, so those two never share state.)
@@ -43,12 +42,3 @@ export function FeedPage() {
     </>
   );
 }
-
-export function MessagesPage() {
-  const me = useMe();
-  return (
-    <div className="p-4 max-w-3xl w-full mx-auto">
-      <Messages meId={me.id} />
-    </div>
-  );
-}