Add support for additional asset types in addon exporter

[anchapin]

Summary

Addon exporter currently only handles texture assets but needs support for sounds, models, and other asset types.

Location

backend/src/services/addon_exporter.py:333

Context

# TODO: Handle other asset types like sounds, models in their respective folders.

Requirements

• Add support for sound asset export (.ogg, .wav files)
• Add support for 3D model export (.geo.json, .json models)
• Add support for animation files
• Organize assets into proper Bedrock folder structure
• Update asset validation to handle new types
• Add tests for new asset type handling

Priority

Medium - Expands addon export functionality for complete Bedrock addon support