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/components/VoiceMessageRecorder.tsx

@@ -197,6 +197,8 @@ export function VoiceMessageRecorder({ onSend, onError }: VoiceRecorderProps) {
           background: color.SurfaceVariant.Container,
           borderRadius: config.radii.R300,
           padding: `${toRem(4)} ${toRem(8)}`,
+          maxWidth: '100%',
+          minWidth: 0,
         }}
       >
         <Box
@@ -212,6 +214,8 @@ export function VoiceMessageRecorder({ onSend, onError }: VoiceRecorderProps) {
         />
         <Text
           size="T200"
+          role="timer"
+          aria-label={`Recording duration ${formatDuration(durationMs)}`}
           style={{
             minWidth: toRem(32),
             fontVariantNumeric: 'tabular-nums',
@@ -230,7 +234,7 @@ export function VoiceMessageRecorder({ onSend, onError }: VoiceRecorderProps) {
           data-voice-waveform
           alignItems="Center"
           gap="100"
-          style={{ height: toRem(20), overflow: 'hidden', flexShrink: 0 }}
+          style={{ height: toRem(20), overflow: 'hidden', flexShrink: 1, minWidth: 0 }}
         >
           {waveformBars.map((h, i) => (
             <div