Created render.go with CGO bindings for mpv_render_context:
- NewRenderContext: Create render context with parameters
- SetUpdateCallback: Register frame update callbacks
- Render: Issue render calls with FBO/dimension params
- Fixed CGO type conversions (int vs mpv_render_param_type)
This enables hardware-accelerated OpenGL rendering of MPV video
frames in the GTK player.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
