A4: self-contained FP32 SyncVSR CTC ONNX (fix dangling external-data)

Add SyncVSR encoder hidden states ONNX (no CTC head, 724 MB)

SyncVSR Vox+LRS2+LRS3 -> ONNX (encoder + CTC head)

Add SyncVSR attention decoder (260 MB)

Add FP16 quantized variant (387 MB, argmax-equiv to FP32)

SyncVSR Vox+LRS2+LRS3 -> ONNX (encoder + CTC head)

SyncVSR Vox+LRS2+LRS3 -> ONNX (encoder + CTC head)

initial commit