Add OBJ File Import/Export Support

[ebowwa]

Summary

This PR adds comprehensive OBJ file format support to Gestalt 3D Editor, enabling import and export of Wavefront OBJ files for improved interoperability with other 3D applications.

Features Implemented

✅ OBJ Import

• Complete OBJ parser supporting vertices, normals, UVs, and faces
• Automatic triangulation of quads and n-gons
• Support for multiple objects per file
• Robust error handling for malformed files
• File size validation (50MB limit)
• Integration with existing menu system

✅ OBJ Export

• Full mesh geometry export with normals and UVs
• Optional MTL material file generation
• Support for multiple mesh export
• Maintains data integrity through round-trip operations
• Integration with existing export dialog

Technical Implementation

Architecture

• Follows existing patterns from gltf-importer.ts
• Leverages existing geometry utilities (buildEdgesFromFaces, calculateVertexNormals)
• Integrates seamlessly with Zustand stores
• Comprehensive TypeScript typing throughout

Files Added

• src/utils/obj-importer.ts - OBJ parsing and scene integration
• src/utils/obj-exporter.ts - Mesh to OBJ conversion
• src/utils/test-obj.ts - Test utilities for validation

Files Modified

• src/features/menu/components/menu-bar.tsx - Added OBJ import menu option

Testing

The implementation includes:

• Comprehensive error handling and validation
• File size and format validation
• Round-trip testing utilities
• Support for various OBJ format variations

Benefits

• Interoperability: Work with models from Blender, Maya, 3ds Max, and other standard 3D tools
• Workflow Integration: Seamless asset exchange with external tools
• User Adoption: Lower barrier to entry with familiar file format support
• Industry Standard: Support for the most widely-used 3D interchange format

Screenshots

The OBJ import option is now available in the Import menu, replacing the previous "OBJ... (soon)" placeholder.

Compatibility

• ✅ No breaking changes
• ✅ Maintains existing T3D functionality
• ✅ TypeScript compilation passes
• ✅ Build succeeds without errors

Closes #1

🤖 Generated with Claude Code

[alightinastorm]

I was just about to review it all, but then saw that it is using an old commit head

Sorry! I was not prepared for someone to contribute - However love that you do!

If you can resolve the conflicts, i'll review it and most likely merge it :D