lotus(#2): address review — ack contract, rate, param precedence

- Document that io.lotus.call_state is request/response and the host must
  ack it (cinny listenAction replies {}) to avoid 10s-timeout churn (H1).
- Throttle 150ms -> 250ms to reduce widget traffic (M1).
- lotusParam: hash fragment wins over query, matching EC's ParamParser (L1).
- Fix the misleading "opaque" id comment; id is userId:deviceId (L2).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lotus/lotusCallState.ts

@@ -12,7 +12,7 @@ import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
 import { LotusWidgetActions, lotusFlag, lotusSendToHost } from "./lotusWidget";
 
 interface ParticipantState {
-  /** Opaque media id (stable per tile). */
+  /** EC media id (`${userId}:${deviceId}`), stable per participant device. */
   id: string;
   /** Matrix user id this media belongs to. */
   userId: string;
@@ -59,7 +59,9 @@ export function startLotusCallState(vm: CallViewModel): () => void {
             ),
       ),
       // `speaking` flips rapidly; cap the send rate and drop no-op repeats.
-      throttleTime(150, undefined, { leading: true, trailing: true }),
+      // 250ms is plenty for speaking rings / mute badges and keeps the
+      // request/response widget traffic modest.
+      throttleTime(250, undefined, { leading: true, trailing: true }),
       distinctUntilChanged((a, b) => JSON.stringify(a) === JSON.stringify(b)),
     )
     .subscribe((participants) => {