Move the state layer onto the host bridge

MuteStates, CallViewModel and LocalMember reached the host through the
widget global. None of them are React components, so they take the bridge
as an explicit parameter: a constructor argument for MuteStates, a field
on CallViewModelOptions, and one on createLocalMembership$'s props.

src/state no longer refers to the widget API.

The conditionals around it mostly disappear: nullHostBridge's observables
are NEVER, so there is nothing to guard, and a request carries its own
reply rather than needing the transport and the original event.

CallViewModelWidget.test.ts drove hangup by emitting on the mocked
widget's action emitter, so it now injects a bridge instead, and checks
that the request is acknowledged.

src/state/CallViewModel/localMember/LocalMember.ts

@@ -53,7 +53,7 @@ import {
   MembershipManagerError,
   UnknownCallError,
 } from "../../../utils/errors.ts";
-import { ElementWidgetActions, widget } from "../../../widget.ts";
+import { type HostBridge } from "../../../HostBridge.ts";
 
 import { PosthogAnalytics } from "../../../analytics/PosthogAnalytics.ts";
 import {
@@ -145,6 +145,8 @@ interface Props {
   >;
   /** Whether to hide the screen-sharing button. */
   hideScreensharing: boolean;
+  /** The application hosting Element Call, to be kept informed of join/leave. */
+  hostBridge: HostBridge;
   logger: Logger;
 }
 
@@ -165,6 +167,7 @@ interface Props {
  * @param props.matrixRTCSession The matrix RTC session to join.
  * @param props.roomId The room ID used as the call identifier in analytics events.
  * @param props.hideScreensharing Whether to hide the screen-sharing button.
+ * @param props.hostBridge The application hosting Element Call.
  * @returns
  *  - publisher: The handle to create tracks and publish them to the room.
  *  - connected$: the current connection state. Including matrix server and livekit server connection. (only considering the livekit server we are using for our own media publication)
@@ -184,6 +187,7 @@ export const createLocalMembership$ = ({
   matrixRTCSession,
   roomId,
   hideScreensharing,
+  hostBridge,
 }: Props): {
   /**
    * This request to start audio and video tracks.
@@ -576,29 +580,24 @@ export const createLocalMembership$ = ({
       }
     });
 
-  // inform the widget about the connect and disconnect intent from the user.
+  // inform the host about the connect and disconnect intent from the user.
   scope
     .behavior(joinAndPublishRequested$.pipe(pairwise(), scope.bind()), [
       undefined,
       joinAndPublishRequested$.value,
     ])
     .subscribe(([prev, current]) => {
-      if (!widget) return;
       // JOIN prev=false (was left) => current-true (now joiend)
       if (!prev && current) {
-        widget.api.transport
-          .send(ElementWidgetActions.JoinCall, {})
-          .catch((e) => {
-            logger.error("Failed to send join action", e);
-          });
+        hostBridge.notifyJoined().catch((e) => {
+          logger.error("Failed to notify the host that we joined", e);
+        });
       }
       // LEAVE prev=false (was joined) => current-true (now left)
       if (prev && !current) {
-        widget.api.transport
-          .send(ElementWidgetActions.HangupCall, {})
-          .catch((e) => {
-            logger.error("Failed to send hangup action", e);
-          });
+        hostBridge.notifyHungUp().catch((e) => {
+          logger.error("Failed to notify the host that we hung up", e);
+        });
       }
     });
 
@@ -845,7 +844,7 @@ interface EnterRTCSessionOptions {
  * @param options - `encryptMedia`: Whether to encrypt media. `matrixRTCMode`: The
  *   Matrix RTC mode to use. `sendNotificationType`: Whether and what kind of
  *   notification to send on join. `callIntent`: The kind of call being placed.
- * @throws If the widget could not send ElementWidgetActions.JoinCall action.
+ * @throws If the host could not be told that we are joining.
  */
 // Exported for unit testing
 export function enterRTCSession(