Add display filter to capture only frames with RA/TA

Use tshark display filter to only capture frames that have RA or TA fields.
This prevents tshark from erroring when encountering management frames
that don't have these fields, which was causing early termination of captures.

Co-authored-by: Cursor <cursoragent@cursor.com>

test_monitor_tshark.sh

@@ -136,8 +136,12 @@ echo "Capturing packets for $DURATION seconds..."
 # Also, wlan.ra/wlan.ta may not be available for all frame types, which can cause tshark to exit with code 1
 # We'll capture both stdout and stderr, but continue even if tshark exits with an error
 set +e  # Temporarily disable exit on error
-# Use -q to suppress packet count output, and continue even if some fields are missing
-CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -q -i "$INTERFACE" -n -T fields \
+# Use -q to suppress packet count output
+# Use display filter to only capture frames that have RA/TA fields
+# This prevents tshark from erroring when it encounters frames without these fields
+CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -q -i "$INTERFACE" -n \
+    -Y "(wlan.ra) || (wlan.ta)" \
+    -T fields \
     -e frame.number \
     -e frame.time \
     -e wlan.ra \