lotus(#4): focus-participant spotlight via widget action

Adds io.lotus.focus_participant (toWidget): the host can pin a participant
to the spotlight by Matrix user id (or clear with userId:null), via a
manual override injected into CallViewModel.spotlightSpeaker$. Replaces
cinny's fragile DOM .click() tile-selector focus hack. Extracts the action
enum into lotusActions.ts (no circular import) and allow-lists Lotus
toWidget actions in initializeWidget. Additive: no-op unless the host
sends the action.

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

src/widget.ts

@@ -22,6 +22,7 @@ import { LazyEventEmitter } from "./LazyEventEmitter";
 import { getUrlParams } from "./UrlParams";
 import { Config } from "./config/Config";
 import { ElementCallReactionEventType } from "./reactions";
+import { LOTUS_TO_WIDGET_ACTIONS } from "./lotus/lotusActions";
 
 // Subset of the actions in element-web
 export enum ElementWidgetActions {
@@ -103,6 +104,8 @@ export const initializeWidget = (
         ElementWidgetActions.JoinCall,
         ElementWidgetActions.HangupCall,
         ElementWidgetActions.DeviceMute,
+        // [lotus] custom toWidget actions handled by the fork (focus, audio-inject)
+        ...LOTUS_TO_WIDGET_ACTIONS,
       ].forEach((action) => {
         api.on(`action:${action}`, (ev: CustomEvent<IWidgetApiRequest>) => {
           ev.preventDefault();