- Replace Lucide icons with accurate brand SVG logos for AI providers (OpenAI, Anthropic, Google, Grok, XAI)\n- Update ProviderIcon tests with comprehensive coverage for new SVG icons\n- Add changeset for accurate provider icons feature\n- Remove obsolete FileEditor test file and related changeset\n- Clean up associated CSS styles
- Create ProviderIcon component with provider-to-icon mappings (OpenAI, Anthropic, Google, etc.)
- Build CustomModelDropdown with icon display, filtering, and keyboard navigation
- Integrate custom dropdown into ModelSelectorTab replacing native select element
- Add CSS styles for provider icons in dropdown items and model badges
- Add comprehensive tests for ProviderIcon, CustomModelDropdown, and ModelSelectorTab
