Apply Finlio cream/terracotta design system

Re-theme dashboard, suivi, plan, and flux pages plus nav from the
claude.ai/design import: warm cream/terracotta/olive palette, pill
nav/buttons/inputs, Caprasimo display font for headings. Dark mode
variant derived to hold the existing WCAG AA contrast ratios since
the import only specified light.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tailwind.config.js

@@ -14,6 +14,7 @@ export default {
         extend: {
             fontFamily: {
                 sans: ['Figtree', ...defaultTheme.fontFamily.sans],
+                display: ['Caprasimo', ...defaultTheme.fontFamily.sans],
             },
             colors: {
                 surface: 'rgb(var(--color-surface) / <alpha-value>)',