fix(calls): app-wide call bar honours room camera/screenshare policy

The persistent call-status bar exposed Video and ScreenShare with no
io.lotus.room_quality check and no share confirmation, bypassing the
in-room bar's gating. Add useRoomCallPolicy and apply the same hiding
plus a "Share your screen?" confirm.

Fixes #26

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/hooks/useRoomCallPolicy.ts

@@ -0,0 +1,28 @@
+import { Room } from 'matrix-js-sdk';
+import { useMemo } from 'react';
+import { useStateEvent } from './useStateEvent';
+import { StateEvent } from '../../types/matrix/room';
+import { RoomQualityContent } from '../utils/callQuality';
+
+export type RoomCallPolicy = {
+  allowCamera: boolean;
+  allowScreenshare: boolean;
+};
+
+/**
+ * [Gitea #26] Shared room-level camera/screenshare policy, read from the
+ * `io.lotus.room_quality` state event. Absent/true = allowed; only an explicit
+ * `false` forbids. Hoisted out of `CallControls` so other call surfaces (e.g.
+ * the app-wide `CallStatus` bar) can apply the same gating.
+ */
+export const useRoomCallPolicy = (room: Room): RoomCallPolicy => {
+  const roomQualityEvent = useStateEvent(room, StateEvent.LotusRoomQuality);
+
+  return useMemo(() => {
+    const roomQuality = roomQualityEvent?.getContent<RoomQualityContent>();
+    return {
+      allowCamera: roomQuality?.allow_camera !== false,
+      allowScreenshare: roomQuality?.allow_screenshare !== false,
+    };
+  }, [roomQualityEvent]);
+};