feat(WIP): update color variables and button styles

This commit includes the following changes:

- Remove the `--card` CSS variable as it is no longer used.
- Update the `--color-disabled-secondary` variable to use the correct value.
- Change the `--color-accent` variable to use a more neutral color.
- Refactor the `buttonVariants` function to accept only the `variant` and `size` props, and apply the `className` prop separately.
- Update the `select` component styles to use the correct text color for focused items.
- Add error handling for the `Logo` component to display a warning if the logo asset is not found.

These changes improve the overall styling and consistency of the application.

src/components/logo.tsx

@@ -88,6 +88,18 @@ export default function Logo({
     );
   }
 
+  if (!logoVar) {
+    console.error(`Logo: Could not find logo asset for ${varName}`);
+    return (
+      <div
+        role='alert'
+        className='p-2 text-red-700 bg-red-100 border border-red-500 rounded-md text-xs'
+      >
+        Error: Logo asset not found. Check console.
+      </div>
+    );
+  }
+
   return (
     <Image
       src={logoVar}