feat(frontend): update theme configuration and color scheme

- Change Tailwind CSS configuration from neutral to slate base color
- Rename style.css to theme.css for better organization
- Update main.js to import the new theme.css file
- Refactor design tokens in style.css with updated color palette
- Replace old color variables with new oklch-based color system
- Add shadcn compatibility variables for component styling
- Update primary, secondary, and accent colors with new values
- Modify destructive, border, input, and ring color definitions

frontend/app/web-gold/components.json

@@ -4,8 +4,8 @@
   "typescript": true,
   "tailwind": {
     "config": "",
-    "css": "src/style.css",
-    "baseColor": "neutral",
+    "css": "src/theme.css",
+    "baseColor": "slate",
     "cssVariables": true,
     "prefix": ""
   },