feat: show encoder implementation in Connection Info, VP9 recommended hint

- Connection Info now shows encoder impl (e.g. libvpx, OpenH264,
  ExternalEncoder) on send-side video tracks alongside quality
  limitation reason
- Amber warning "VP9 is recommended" when H.264 is selected

packages/web/src/components/voice/ConnectionInfoPopover.tsx

@@ -93,16 +93,19 @@ function VideoTrackRow({ track }: { track: VideoTrackStat }) {
           {track.codec && <span className="text-txt-tertiary ml-2">{track.codec}</span>}
         </span>
       </div>
-      {(resolution || track.fps !== null || track.qualityLimitation || track.simulcastLayer) && (
+      {(resolution || track.fps !== null || track.qualityLimitation || track.simulcastLayer || track.encoderImpl) && (
         <div className="flex items-center justify-between pl-3">
           <span className="text-[11px] text-txt-tertiary">
             {resolution && `${resolution}`}
             {track.fps !== null && ` @${track.fps}`}
           </span>
           <span className="text-[11px] text-txt-tertiary">
-            {track.direction === 'send' && track.qualityLimitation && track.qualityLimitation !== 'none'
+            {track.direction === 'send' && (() => {
-              ? track.qualityLimitation
+              const parts: string[] = [];
-              : ''}
+              if (track.encoderImpl) parts.push(track.encoderImpl);
+              if (track.qualityLimitation && track.qualityLimitation !== 'none') parts.push(track.qualityLimitation);
+              return parts.join(' · ') || null;
+            })()}
             {track.direction === 'recv' && track.simulcastLayer
               ? track.simulcastLayer
               : ''}

packages/web/src/components/voice/ScreenShareSettingsPopover.tsx

@@ -199,6 +199,11 @@ export function ScreenShareSettingsPopover({ open, onClose, anchorRef }: ScreenS
               </button>
             ))}
           </div>
+          {config.codec !== 'vp9' && (
+            <div className="text-[10px] text-accent-amber/80 mt-1">
+              VP9 is recommended for most setups
+            </div>
+          )}
         </div>
 
         {/* Bitrate Override */}

packages/web/src/hooks/useTrackStats.ts

@@ -26,6 +26,7 @@ export interface VideoTrackStat {
   participantName: string | null;
   bitrate: number;
   codec: string | null;
+  encoderImpl: string | null;
   width: number | null;
   height: number | null;
   fps: number | null;
@@ -362,6 +363,7 @@ export function useTrackStats(enabled: boolean): TrackStatsSnapshot | null {
                   participantName: null,
                   bitrate,
                   codec,
+                  encoderImpl: report.encoderImplementation ?? null,
                   width,
                   height,
                   fps,
@@ -493,6 +495,7 @@ export function useTrackStats(enabled: boolean): TrackStatsSnapshot | null {
                   participantName: identity.participantName,
                   bitrate,
                   codec,
+                  encoderImpl: null,
                   width,
                   height,
                   fps,