feat: add __init__.py files to enable module imports

Add __init__.py files to vibevoice/modular and vibevoice/processor
directories to properly export classes and enable package imports.

This allows users to import the package after installation:
- from vibevoice import VibeVoiceStreamingForConditionalGenerationInference
- from vibevoice.modular import VibeVoiceStreamingConfig
- from vibevoice.processor import VibeVoiceStreamingProcessor

Fixes import errors when using `pip install -e .`

vibevoice/__init__.py

@@ -0,0 +1,16 @@
+# vibevoice/__init__.py
+from vibevoice.modular import (
+    VibeVoiceStreamingForConditionalGenerationInference,
+    VibeVoiceStreamingConfig,
+)
+from vibevoice.processor import (
+    VibeVoiceStreamingProcessor,
+    VibeVoiceTokenizerProcessor,
+)
+
+__all__ = [
+    "VibeVoiceStreamingForConditionalGenerationInference",
+    "VibeVoiceStreamingConfig",
+    "VibeVoiceStreamingProcessor",
+    "VibeVoiceTokenizerProcessor",
+]