chore(web): record the useProgressToasts return-type exception

Copilot's second pass accepted every code fix and re-raised one item:
useProgressToasts is the only extracted hook that returns nothing, which
contradicts #2128's "each hook returns one object" criterion, and the
disagreement was recorded nowhere a reader would find it.

Its ask was either a result object or an explicit exception. Taking the
second: the hook subscribes, shows toasts and unsubscribes, and the only
state it owns is toast-id bookkeeping the caller must not see, so `{}`
would advertise an API that is not there. The criterion exists to stop a
hook handing back a long list of loose values — useTabUiState's
twenty-two is the case it was written against, and that one does return
a bundled object.

Noted in the hook's own doc block (so it reads as a decision rather than
an oversight) and on #2128 itself, so the acceptance criteria and the
implementation agree.

Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/hooks/useProgressToasts.ts

@@ -32,6 +32,13 @@ export type InspectorClientEventSource = Pick<
  * are the at-a-glance, in-context signal. Toasts are keyed by progress stream
  * (see `progressToastId`) and replaced per tick, so a chatty server updates one
  * toast rather than stacking one per tick.
+ *
+ * Returns nothing — the recorded exception to #2128's "each hook returns one
+ * object" criterion, which exists to stop a hook handing back a long list of
+ * loose values (`useTabUiState`'s twenty-two is the case it was written
+ * against). This hook subscribes, shows toasts and unsubscribes; the only
+ * state it owns is toast-id bookkeeping the caller must not see. An empty
+ * object would advertise an API that is not there.
  */
 export function useProgressToasts(
   inspectorClient: InspectorClientEventSource | null,