redesign: apply correct Editorial Fresh design system

- Fix palette: #E85A4F accent, #FFFBF5 cream, #1A1A1A ink (was wrong values)
- Remove all border-radius (zero radius everywhere per design spec)
- Sidebar: cream-dark #F5F0E8 bg with accent-left active indicator
- card-editorial: white bg, 4px accent top bar via absolute div
- Buttons: ink bg → accent hover + translateY(-1px)
- LoginPage: correct split layout with Editorial Fresh tokens
- Add .btn-primary / .btn-outline / .input-editorial / .editorial-tag classes
- Fraunces + DM Sans correctly applied everywhere

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

frontend/tailwind.config.js

@@ -4,28 +4,38 @@ export default {
   theme: {
     extend: {
       colors: {
-        coral: '#FF6B4A',
-        cream: '#FAF8F3',
-        ink: '#1A1A2E',
-        muted: '#8B8B9A',
-        border: '#E8E4DE',
-        // Brand alias per compatibilità con componenti esistenti
-        brand: {
-          50: '#fff4f1',
-          100: '#ffe4dd',
-          200: '#ffc4b5',
-          300: '#ff9d85',
-          400: '#ff7a5c',
-          500: '#FF6B4A',
-          600: '#e8522f',
-          700: '#c43f22',
-          800: '#9e3219',
-          900: '#7c2912',
-        },
+        cream:        '#FFFBF5',
+        'cream-dark': '#F5F0E8',
+        ink:          '#1A1A1A',
+        'ink-light':  '#4A4A4A',
+        'ink-muted':  '#7A7A7A',
+        accent:       '#E85A4F',
+        'accent-hover':'#D14940',
+        'accent-light':'#FFF0EE',
+        border:       '#E5E0D8',
+        'border-strong':'#D0C9BD',
+        success:      '#2D7A4F',
+        // Legacy aliases
+        coral:        '#E85A4F',
+        muted:        '#7A7A7A',
       },
       fontFamily: {
-        serif: ['Fraunces', 'serif'],
-        sans: ['DM Sans', 'sans-serif'],
+        serif: ['Fraunces', 'Georgia', 'serif'],
+        sans:  ['DM Sans', 'sans-serif'],
+      },
+      borderRadius: {
+        DEFAULT: '0',
+        none:    '0',
+        sm:      '0',
+        md:      '0',
+        lg:      '0',
+        xl:      '0',
+        '2xl':   '0',
+        full:    '9999px', // keep for avatars/circles
+      },
+      letterSpacing: {
+        tight:    '-0.02em',
+        editorial: '0.1em',
       },
     },
   },