fix: screenshare codec fallback, native FPS, and connection info

- Gaming mode uses H.264 primary (hardware NVENC encoding, zero CPU
  impact on games). Text mode uses VP9 primary with H.264 backup
  and SIMULCAST policy for Safari compatibility.
- Fix native mode starting at 30fps by decoupling frameRate constraint
  from resolution constraint in both screenShare.ts overdrive and
  useLiveKit.ts updateActiveTracks.
- Filter paused backup codec tracks in Connection Info stats so dead
  0kbps entries don't show alongside active codec tracks.

packages/web/src/hooks/useTrackStats.ts

@@ -511,14 +511,30 @@ export function useTrackStats(enabled: boolean): TrackStatsSnapshot | null {
         network.packetLoss = (totalPacketsLost / totalPackets) * 100;
       }
 
-      // ── Step F: Cleanup stale prevSample entries ──
+      // ── Step F: Filter paused backup codec tracks ──
+      // With backupCodec enabled, the publisher may have two concurrent outbound
+      // video tracks for the same source (e.g. VP9 + H.264). When one is paused
+      // by dynacast (0 bitrate), hide it if an active sibling exists.
+      const filteredVideoTracks = videoTracks.filter((track) => {
+        if (track.direction !== 'send' || track.bitrate > 0) return true;
+        const hasActiveSibling = videoTracks.some(
+          (other) =>
+            other !== track &&
+            other.direction === 'send' &&
+            other.source === track.source &&
+            other.bitrate > 0,
+        );
+        return !hasActiveSibling;
+      });
+
+      // ── Step G: Cleanup stale prevSample entries ──
       for (const key of prev.keys()) {
         if (!seenKeys.has(key)) {
           prev.delete(key);
         }
       }
 
-      setSnapshot({ network, audioTracks, videoTracks });
+      setSnapshot({ network, audioTracks, videoTracks: filteredVideoTracks });
     };
 
     poll();