fix(call): one-row call bar on phones; screenshare-audio mute only when useful (#265, #277)

#265: in the compact layout (phones, narrow windows) the control bar
stacked into four rows (~330px, 40% of a portrait phone). It is now one
row: mic, deafen, camera, chat, soundboard, More and an icon-only End.
Screenshare, its audio mute and fullscreen move into More; Share Screen
is only offered where getDisplayMedia exists. (The self-view comes from
the fork, lotus.27.)

#277: "Mute Screenshare Audio" showed whenever screensharing was allowed,
as a speaker icon that did nothing. It now shows while the fork reports
remote screenshare audio (io.lotus.screenshare_audio_state), or while it
is muted, so a hidden mute cannot silence the next share.

Fixes #265
Fixes #277

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/plugins/call/screenshareAudioState.test.ts

@@ -0,0 +1,12 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { parseScreenshareAudioState } from './CallControl';
+
+test('parseScreenshareAudioState: reads present, ignores anything else (#277)', () => {
+  assert.equal(parseScreenshareAudioState({ present: true }), true);
+  assert.equal(parseScreenshareAudioState({ present: false }), false);
+  assert.equal(parseScreenshareAudioState({ present: 'yes' }), undefined);
+  assert.equal(parseScreenshareAudioState({}), undefined);
+  assert.equal(parseScreenshareAudioState(null), undefined);
+  assert.equal(parseScreenshareAudioState('present'), undefined);
+});