Fix DesignToken interface compatibility in generate-theme-tool

Add missing cssVar property to generated tokens.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dallasbpeters

src/tools/generate-theme-tool.ts

@@ -99,20 +99,23 @@ class GenerateThemeTool extends Tool {
 
       tokens.push({
         name: `op-color-${family}-h`,
+        cssVar: `--op-color-${family}-h`,
         value: String(hsl.h),
         category: 'color',
         description: `${family} color hue (HSL) - drives all ${family} scale tokens`
       });
 
       tokens.push({
         name: `op-color-${family}-s`,
+        cssVar: `--op-color-${family}-s`,
         value: `${hsl.s}%`,
         category: 'color',
         description: `${family} color saturation (HSL)`
       });
 
       tokens.push({
         name: `op-color-${family}-l`,
+        cssVar: `--op-color-${family}-l`,
         value: `${hsl.l}%`,
         category: 'color',
         description: `${family} color lightness (HSL)`