fix: add @source directives so Tailwind v4 scans all component files

Without explicit @source paths, Tailwind v4 auto-detection can miss
app/, components/, and lib/ directories in production builds, causing
utility classes to be stripped from the output CSS.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/globals.css

@@ -1,6 +1,10 @@
 @import "tailwindcss";
 @import "flag-icons/css/flag-icons.min.css";
 
+@source "../app/**/*.{ts,tsx}";
+@source "../components/**/*.{ts,tsx}";
+@source "../lib/**/*.{ts,tsx}";
+
 @theme inline {
   --color-bg: #040d08;
   --color-card: #0a1810;