feat: update notice after a server update, keep the open tab on reload, chunked Whisper in Quick Dump, compact emoji picker

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

frontend/src/lib/useUpdateCheck.ts

@@ -0,0 +1,56 @@
+import { useEffect, useRef, useState } from 'react';
+import { APP_BUILD } from '../version';
+
+const CHECK_EVERY_MS = 15 * 60 * 1000;
+
+export interface AvailableUpdate {
+  version: string;
+  build: string;
+}
+
+// Notices when the server runs a newer build than this page (version.json, written at build time and
+// never cached): when the tab or the installed app comes back to the foreground, every 15 minutes and
+// when the realtime connection is back after a server restart. "Später" hides it until the next build.
+export function useUpdateCheck() {
+  const [update, setUpdate] = useState<AvailableUpdate | null>(null);
+  const dismissedRef = useRef('');
+
+  useEffect(() => {
+    if (!APP_BUILD) return; // dev server: no version.json
+    let busy = false;
+    const check = async () => {
+      if (busy || document.visibilityState === 'hidden') return;
+      busy = true;
+      try {
+        const res = await fetch(`/version.json?t=${Date.now()}`, { cache: 'no-store' });
+        const live = (await res.json()) as Partial<AvailableUpdate>;
+        if (live.build && live.build !== APP_BUILD && live.build !== dismissedRef.current) {
+          setUpdate({ version: live.version || '', build: live.build });
+        }
+      } catch {
+        // offline, or an older server without version.json (answers with the page): try again later
+      } finally {
+        busy = false;
+      }
+    };
+    const onVisible = () => document.visibilityState === 'visible' && void check();
+    const onWsStatus = (e: Event) => (e as CustomEvent<{ connected?: boolean }>).detail?.connected && void check();
+    const timer = window.setInterval(() => void check(), CHECK_EVERY_MS);
+    document.addEventListener('visibilitychange', onVisible);
+    window.addEventListener('focus', onVisible);
+    window.addEventListener('mindsift:ws:status', onWsStatus);
+    void check();
+    return () => {
+      window.clearInterval(timer);
+      document.removeEventListener('visibilitychange', onVisible);
+      window.removeEventListener('focus', onVisible);
+      window.removeEventListener('mindsift:ws:status', onWsStatus);
+    };
+  }, []);
+
+  const dismiss = () => {
+    if (update) dismissedRef.current = update.build;
+    setUpdate(null);
+  };
+  return { update, dismiss };
+}