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/lotus/lotusActions.ts

@@ -0,0 +1,26 @@
+/*
+Copyright 2026 Lotus Guild
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+/**
+ * Custom widget actions exchanged between the Lotus host (cinny) and this fork.
+ * Kept dependency-free so both `widget.ts` and `lotus/*` can import it without
+ * a circular dependency.
+ */
+export enum LotusWidgetActions {
+  /** fromWidget: in-call per-participant speaking / mute state. */
+  CallState = "io.lotus.call_state",
+  /** toWidget: pin/spotlight (or clear, with userId=null) a participant. */
+  FocusParticipant = "io.lotus.focus_participant",
+  /** toWidget: mix an audio clip into the local published mic track. */
+  InjectAudio = "io.lotus.inject_audio",
+}
+
+/** toWidget Lotus actions that must be allow-listed in `initializeWidget`. */
+export const LOTUS_TO_WIDGET_ACTIONS: LotusWidgetActions[] = [
+  LotusWidgetActions.FocusParticipant,
+  LotusWidgetActions.InjectAudio,
+];