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/GifPicker.tsx

@@ -7,6 +7,7 @@ import { useSetting } from '../state/hooks/settings';
 import { settingsAtom } from '../state/settings';
 
 const PICKER_WIDTH = 312;
+const PICKER_WIDTH_CSS = `min(${PICKER_WIDTH}px, calc(100vw - 16px))`;
 
 type GifPickerInnerProps = {
   onSelect: (url: string, width: number, height: number) => void;
@@ -31,7 +32,7 @@ function GifPickerInner({ onSelect, requestClose, lotusTerminal }: GifPickerInne
   );
 
   return (
-    <Box direction="Column" style={{ width: `${PICKER_WIDTH}px` }}>
+    <Box direction="Column" style={{ width: PICKER_WIDTH_CSS }}>
       {lotusTerminal && (
         <div
           style={{
@@ -88,7 +89,7 @@ export function GifPicker({ apiKey, onSelect, requestClose }: GifPickerProps) {
         overflow: 'hidden',
         boxShadow:
           '0 4px 24px color-mix(in srgb, var(--lt-accent-orange) 10%, transparent), 0 0 0 1px color-mix(in srgb, var(--lt-accent-orange) 8%, transparent)',
-        width: `${PICKER_WIDTH}px`,
+        width: PICKER_WIDTH_CSS,
       }
     : {
         background: color.Surface.Container,
@@ -96,14 +97,14 @@ export function GifPicker({ apiKey, onSelect, requestClose }: GifPickerProps) {
         borderRadius: config.radii.R400,
         overflow: 'hidden',
         boxShadow: color.Other.Shadow,
-        width: `${PICKER_WIDTH}px`,
+        width: PICKER_WIDTH_CSS,
       };
 
   return (
     <FocusTrap
       focusTrapOptions={{
         initialFocus: false,
-        returnFocusOnDeactivate: false,
+        returnFocusOnDeactivate: true,
         onDeactivate: requestClose,
         clickOutsideDeactivates: true,
         allowOutsideClick: true,