Validate length-prefixed NAL headers consistently with Annex B input

tools/chatgui-android/app/src/test/java/com/utun/chat/data/H264AnnexBTest.kt

@@ -30,4 +30,10 @@ class H264AnnexBTest {
         assertThrows(IllegalArgumentException::class.java) { H264AnnexB.keyFrame(byteArrayOf(0, 0, 1, 0x61, 0x11), sps + pps) }
         assertThrows(IllegalArgumentException::class.java) { H264AnnexB.normalize(ByteArray(H264AnnexB.MAX_FRAME + 1)) }
     }
+
+    @Test fun lengthPrefixedNalUsesTheSameForbiddenBitValidationAsAnnexB() {
+        val invalid = byteArrayOf(0, 0, 0, 2, -1, 1)
+        assertThrows(IllegalArgumentException::class.java) { H264AnnexB.normalize(invalid) }
+        assertThrows(IllegalArgumentException::class.java) { H264AnnexB.normalize(byteArrayOf(0, 0, 0, 1, -1, 1)) }
+    }
 }