fix: negative_prompt inline (multiline:false) + VAE filename v1-44.pth not v1-44k.pth

- SelvaSampler: multiline:false puts negative_prompt inline above sliders
- SelvaModelLoader: VAE filenames in download_utils are v1-16.pth/v1-44.pth,
  not v1-{mode}.pth (mode includes the 'k' suffix)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nodes/selva_sampler.py

@@ -16,7 +16,7 @@ class SelvaSampler:
                     "tooltip": "CLIP text for audio generation. Leave empty to reuse the prompt from SelvaFeatureExtractor.",
                 }),
                 "negative_prompt": ("STRING", {
-                    "default": "", "multiline": True,
+                    "default": "", "multiline": False,
                     "tooltip": "Sounds to steer away from, e.g. 'wind noise, background music'.",
                 }),
                 "duration": ("FLOAT", {