XAML: Show color swatches for named colors (e.g. Red, CornflowerBlue)

Summary

The XAML language server currently shows color swatches only for hex color literals (e.g. #FF0000). Named WinUI colors like Red, CornflowerBlue, DarkSlateGray should also display inline color swatches in the editor.

Current state

• XamlColor.cs parses hex literals and returns ColorInformation to the LSP client
• XamlTypeSystem.GetNamedColors() already discovers named color constants via Roslyn (e.g. Microsoft.UI.Colors.Red)
• However, Roslyn cannot evaluate property getters at design time, so the actual RGBA values for named colors are not available from the type system alone

Proposed approach

Import a build-time lookup table of named color → RGBA mappings from the WinAppSDK source (or a generated resource). This table would be used by XamlColor to resolve named colors to their swatch values without requiring runtime evaluation.

Related

• PR #50 (XAML language service integration)
• server/src/WinUiXaml.LanguageServer/XamlColor.cs
• server/src/WinUiXaml.Workspace/XamlTypeSystem.cs