useAsync re-threw errors after storing them in Error state. Any call site
that discards the returned Promise (e.g. fire-and-forget useEffect calls
like loadSrc() or loadThumbSrc()) produced an 'Uncaught (in promise)'
console error — notably 'Mismatched SHA-256 digest' from encrypted media
decryption failures.

The error is already fully handled: it is stored in AsyncStatus.Error state
and components surface it via a retry button. The re-throw added no value
and only caused noise / unhandled rejection warnings.

Update the test accordingly — the .catch(() => {}) guard was only needed to
silence the re-throw and is no longer necessary.

There is a timing window between when the SDK refreshes its access
token (tokenRefreshFunction resolves and pushSessionToSW is called)
and when the resulting setSession postMessage is processed by the SW.
Media requests that land in this window carry the stale token and
receive 401. The browser then retries those image/video loads, hitting
the SW again with the same stale token — producing the repeated 401
bursts visible in the console.

fetchMediaWithRetry() resolves this by retrying once on 401: it
re-checks the in-memory sessions map (and preloadedSession fallback)
for a different access token. By the time the retry runs, setSession
will normally have been processed and the map will hold the new token.
Applied consistently across all four branches of the fetch handler.

- useAsyncCallback: re-throw in catch to preserve rejection semantics;
  add no-op .catch wrapper in useAsyncCallback to suppress unhandled
  rejection warnings for fire-and-forget callers
- useAsyncCallback.test: expect rejects.toBe(boom) to assert rejection
- loginUtil: use != null guards for refresh_token / expires_in_ms to
  correctly handle zero/falsy-but-present values
- initMatrix: use typeof === 'number' guard for expires_in_ms expiry calc
- ClientRoot: pass activeSession.userId to both pushSessionToSW calls
  so the SW session record keeps a complete userId

Resolve stash conflict in DevelopTools.tsx — keep the improved Rotate
Encryption Sessions description and success message text from the
stashed changes.

Add an immediate synchronous sendSessionToSW() call in index.tsx before
React mounts. When the SW is already active (normal page reload),
navigator.serviceWorker.controller is set and the postMessage is sent
before createRoot().render() runs and before any <img> elements fire
fetch events. This discards the stale preloadedSession in the SW (which
could be from a previous token that is no longer current) before the
first thumbnail/media fetches arrive, preventing the race condition that
produced 401 errors on initial load with Retry buttons.

persistSession was called fire-and-forget inside setSession. If the
browser killed the service worker between the setSession message being
processed and the caches.put call completing, the persisted session cache
would retain the previous (stale) token. On the next SW restart, the
activate handler loads this stale session into preloadedSession, causing
media requests to 401 until the retry path eventually obtains a fresh
token from the live page via requestSessionWithTimeout.

Using event.waitUntil on the persist/clear operation ensures the browser
keeps the SW alive until the cache write resolves, eliminating the race
window that could leave the cache in an inconsistent state.