fix: add missing sidebar CSS variables to components package

- Add sidebar color CSS custom properties to @theme section
- Add sidebar base colors to :root for light mode
- Add sidebar colors to .dark for dark mode
- Fixes sidebar menu rendering issues after shadcn upgrade

Agent-Logs-Url: https://github.com/objectstack-ai/objectui/sessions/d18adb23-dd47-4f83-9bfb-7c147e93f672

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Claude

packages/components/src/index.css

@@ -33,6 +33,14 @@
   --color-popover-foreground: hsl(var(--popover-foreground));
   --color-card: hsl(var(--card));
   --color-card-foreground: hsl(var(--card-foreground));
+  --color-sidebar: hsl(var(--sidebar));
+  --color-sidebar-foreground: hsl(var(--sidebar-foreground));
+  --color-sidebar-primary: hsl(var(--sidebar-primary));
+  --color-sidebar-primary-foreground: hsl(var(--sidebar-primary-foreground));
+  --color-sidebar-accent: hsl(var(--sidebar-accent));
+  --color-sidebar-accent-foreground: hsl(var(--sidebar-accent-foreground));
+  --color-sidebar-border: hsl(var(--sidebar-border));
+  --color-sidebar-ring: hsl(var(--sidebar-ring));
 
   /* Chart colors */
   --color-chart-1: hsl(var(--chart-1));
@@ -82,6 +90,16 @@
   --chart-4: 43 74% 66%;
   --chart-5: 27 87% 67%;
 
+  /* Sidebar colors */
+  --sidebar: 0 0% 98%;
+  --sidebar-foreground: 240 5.3% 26.1%;
+  --sidebar-primary: 240 5.9% 10%;
+  --sidebar-primary-foreground: 0 0% 98%;
+  --sidebar-accent: 240 4.8% 95.9%;
+  --sidebar-accent-foreground: 240 5.9% 10%;
+  --sidebar-border: 220 13% 91%;
+  --sidebar-ring: 217.2 91.2% 59.8%;
+
   font-family: 'Inter', ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
 }
 
@@ -119,6 +137,16 @@
   --chart-3: 30 80% 55%;
   --chart-4: 280 65% 60%;
   --chart-5: 340 75% 55%;
+
+  /* Sidebar colors for dark mode */
+  --sidebar: 240 5.9% 10%;
+  --sidebar-foreground: 240 4.8% 95.9%;
+  --sidebar-primary: 224.3 76.3% 48%;
+  --sidebar-primary-foreground: 0 0% 100%;
+  --sidebar-accent: 240 3.7% 15.9%;
+  --sidebar-accent-foreground: 240 4.8% 95.9%;
+  --sidebar-border: 240 3.7% 15.9%;
+  --sidebar-ring: 217.2 91.2% 59.8%;
 }
 
 * {