fix(a11y): correct call-control aria + picker/recorder/live-chip UX (DP7-DP12)

DP7: fix inverted Deafen/Undeafen aria-label on the sound button so it
  matches the action and tooltip.
DP8: add aria-pressed to Sound/Video/ScreenShare toggles and align the
  Microphone toggle to the same "pressed = feature on/active" semantic.
DP9: return focus to the trigger when the GifPicker closes and cap its
  fixed width to min(312px, calc(100vw - 16px)) so it can't overflow
  narrow viewports.
DP10: drop redundant mouse-only clear onClick nested inside the search
  filter Chip buttons (parent chip/menu already performs the clear);
  the cross icons are now purely decorative.
DP11: constrain the voice recorder widget and let the waveform shrink so
  it fits a narrow composer, and expose the live duration as a role="timer"
  snapshot instead of spamming a screen reader every 100ms.
DP12: announce the live-call participant count via a visually-hidden
  role="status" region.

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

src/app/features/call-status/styles.css.ts

@@ -5,6 +5,18 @@ export const LiveChipText = style({
   color: color.Critical.Main,
 });
 
+export const SrOnly = style({
+  position: 'absolute',
+  width: 1,
+  height: 1,
+  padding: 0,
+  margin: -1,
+  overflow: 'hidden',
+  clip: 'rect(0, 0, 0, 0)',
+  whiteSpace: 'nowrap',
+  border: 0,
+});
+
 export const CallStatus = style([
   {
     padding: `${toRem(6)} ${config.space.S200}`,