fix: Correct CSS Modules selector purity for focus styles

- Modifies the focus selectors in `cosmicfest.module.css` to use `:global()` to comply with CSS Modules restrictions.
- This resolves the build failure.

next/styles/cosmicfest.module.css

@@ -279,7 +279,7 @@
 }
 
 /* Accessibility: Focus indicator */
-a:focus, button:focus, input:focus {
+:global(a:focus), :global(button:focus), :global(input:focus) {
   outline: 2px solid #3498db;
   outline-offset: 2px;
 }