feat: add OmniVoice Mix Voices node for blended speaker cloning

Concatenates 2-3 reference audio clips (with per-voice duration weights)
to create a blended speaker embedding. Merges transcripts for ref_text.
Handles mismatched sample rates and mono conversion automatically.

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

__init__.py

@@ -1,10 +1,11 @@
-from .nodes import OmniVoiceModelLoader, OmniVoiceGenerate, OmniVoiceEpubLoader, OmniVoiceVoicePreset
+from .nodes import OmniVoiceModelLoader, OmniVoiceGenerate, OmniVoiceEpubLoader, OmniVoiceVoicePreset, OmniVoiceMixVoices
 
 NODE_CLASS_MAPPINGS = {
     "OmniVoiceModelLoader": OmniVoiceModelLoader,
     "OmniVoiceGenerate": OmniVoiceGenerate,
     "OmniVoiceEpubLoader": OmniVoiceEpubLoader,
     "OmniVoiceVoicePreset": OmniVoiceVoicePreset,
+    "OmniVoiceMixVoices": OmniVoiceMixVoices,
 }
 
 NODE_DISPLAY_NAME_MAPPINGS = {
@@ -12,6 +13,7 @@ NODE_DISPLAY_NAME_MAPPINGS = {
     "OmniVoiceGenerate": "OmniVoice Generate",
     "OmniVoiceEpubLoader": "OmniVoice EPUB Loader",
     "OmniVoiceVoicePreset": "OmniVoice Voice Preset",
+    "OmniVoiceMixVoices": "OmniVoice Mix Voices",
 }
 
 __all__ = ["NODE_CLASS_MAPPINGS", "NODE_DISPLAY_NAME_MAPPINGS"]