feat(design-system): add type scale, spacing rhythm and font tokens

Apply the Phase 2 warm-premium base additively (no existing page changes):
- tailwind.config.ts: add fontSize roles (display, h1, h2, h3, title, body-lg,
  body, small, caption, overline) with line-height/tracking/weight; add
  fontFamily (sans/latin = Museo, arabic = Dubai); add section-sm/section-lg
  spacing rhythm.
- globals.css: add Arabic-safe .eyebrow utility (uppercase + tracking on Latin,
  neutralised for html[lang="ar"]).

Colors and fonts unchanged. Verified: tsc clean, eslint clean, tailwind build
generates the new utilities with correct values.

app/globals.css

@@ -168,6 +168,18 @@ html[lang="ar"] {
   font-family: var(--font-dubai), sans-serif;
 }
 
+/* Eyebrow / overline label. Latin gets uppercase + tracking; Arabic keeps
+   normal case and spacing so joined letterforms are not broken. */
+.eyebrow {
+  text-transform: uppercase;
+  letter-spacing: 0.14em;
+}
+
+html[lang="ar"] .eyebrow {
+  text-transform: none;
+  letter-spacing: normal;
+}
+
 @layer base {
   * {
     @apply border-border;