docs(cortex-gui): comprehensive feature roadmap comparing Zed and VSCode (#325)

- Analyzed Zed (217+ crates) and VSCode (93+ contributions) for feature comparison
- Identified 15 high-impact features to implement or improve
- Prioritized by performance impact: Rope data structure, VirtualList pooling, Sum tree
- AI features: Advanced edit predictions, True multi-buffer editing
- Collaboration: CRDT-based real-time editing with presence
- Performance: GPU-accelerated minimap, incremental syntax highlighting
- Workflow: Enhanced problem matchers, keybinding editor, performance profiler
- Detailed implementation specifications with TypeScript interfaces
- Estimated timeline: 17 weeks for full implementation

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt