Extract shared parseHexColor utility

[portwatcher]

Summary

The parseHexColor function (converts CSS hex color strings to Godot r,g,b,a format) is currently duplicated in three component files:

• packages/html/src/components/Span.ts
• packages/html/src/components/Button.ts
• packages/html/src/components/Input.ts

Extract this into a shared utility at packages/html/src/utils/colorParser.ts and import it from each component.

Additional scope

• Support named CSS colors (red, blue, etc.) via a lookup table
• Support rgb() / rgba() / hsl() formats
• Add unit tests for the color parser

[portwatcher]

Confirmed: parseHexColor is now duplicated in 3 component files after 89f93c6:

• packages/html/src/components/Span.ts
• packages/html/src/components/Button.ts
• packages/html/src/components/Input.ts

Priority should increase as more components are added.

[portwatcher]

Status update (2026-03-03):

The core extraction is done — parseHexColor lives in packages/html/src/utils/colorParser.ts and all components import from the shared module (no duplication). See commit 447fe2b.

Remaining (additional scope):

• Named CSS colors (red, blue, etc.) via lookup table
• rgb() / rgba() / hsl() format support
• Unit tests for the color parser

Consider narrowing this issue's title/scope to the additional format support, since the extraction itself is complete.