theme: lift text-faint to meet WCAG AA contrast

text-faint #6b7280 on bg #060a13 measures ~4.06:1 contrast — under the
4.5:1 normal-text threshold — which fails Lighthouse's color-contrast
audit and drops the accessibility score to 0.90 on /pricing and
/privacy (the only pages currently using this token).

#828b9b yields ~5.66:1, clears AA with margin, and stays visually
distinct from text-muted (#9aa3b2, ~7.8:1) so the design hierarchy
between text / text-muted / text-faint is preserved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tailwind.config.mjs

@@ -25,7 +25,7 @@ export default {
         text: {
           DEFAULT: '#e8eaed',
           muted: '#9aa3b2',
-          faint: '#6b7280',
+          faint: '#828b9b',
         },
       },
       fontFamily: {