Initial release: ComfyUI-UniverSR

ComfyUI nodes for UniverSR (ICASSP 2026) — vocoder-free audio
super-resolution (8/12/16/24 kHz → 48 kHz) via flow matching.

- UniverSR Model Loader: presets auto-download to models/universr,
  plus local dir / raw .pth (from_local) loading, with caching.
- UniverSR Super-Resolution: chunked overlap-add for long audio,
  per-channel stereo, seed control with global-RNG isolation,
  wet/dry blend, and an optional before/after spectrogram.
- Vendors the universr inference package under vendor/ (prefers an
  installed copy); only extra dep beyond ComfyUI's stack is torchdiffeq.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

vendor/universr/flow/loss.py

@@ -0,0 +1,9 @@
+import torch
+import torch.nn.functional as F
+
+
+def flow_matching_loss(predicted_vf: torch.Tensor, target_vf: torch.Tensor) -> torch.Tensor:
+    """
+    Flow matching loss; L2 loss between estimated and target vector field.
+    """
+    return F.mse_loss(predicted_vf, target_vf)