Split view, personal modes, budget warnings, server move script

- Up to three chats side by side (#/s/a+b+c), "Open beside" in the sidebar menu
- File manager tabs of a chat stored per user on the server (/sessions/{id}/tabs)
- Personal modes for every user (Settings → My modes, /account/modes)
- Budget meters (total, provider, images, opencode Go windows) with push warnings
  for admins at the warning share and 100 %, shown in the status overlay
- scripts/move-server.sh: move to another Docker host with bind mounts (Unraid);
  scripts/smoke-test.sh

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/components/ChatView.tsx

@@ -136,7 +136,7 @@ function RefineFeedback({ text }: { text: string }) {
   );
 }
 
-export function ChatView({ sessionId, onMenu }: { sessionId: string; onMenu: () => void }) {
+export function ChatView({ sessionId, onMenu, onClosePane }: { sessionId: string; onMenu: () => void; onClosePane?: () => void }) {
   const t = useT();
   const session = useStore((s) => s.sessionById[sessionId]);
   const messages = useStore((s) => s.messages[sessionId] ?? EMPTY);
@@ -368,6 +368,11 @@ export function ChatView({ sessionId, onMenu }: { sessionId: string; onMenu: ()
             </button>
           </>
         )}
+        {onClosePane && (
+          <button className="small ghost" onClick={onClosePane} title={t("chat.closePane")} aria-label={t("chat.closePane")}>
+            <Icon name="close" />
+          </button>
+        )}
       </div>
       <ChatTabBar state={tabs} />
       <ChatTabPanes state={tabs} />