feat(01-04): design tokens Tailwind v4 + wire ClientDashboard in page.tsx

- globals.css: aggiunto @theme con palette light & clean (primary, secondary,
  tertiary, bg-subtle, border-light, accent, success, warning, info)
- app/c/[token]/page.tsx: import ClientDashboard, generateMetadata dinamico,
  React.cache() per deduplicare DB call tra metadata e render

src/app/globals.css

@@ -1,26 +1,48 @@
 @import "tailwindcss";
 
-:root {
-  --background: #ffffff;
-  --foreground: #171717;
-}
-
+/* =========================================================
+   Design tokens — light & clean palette (Tailwind v4 @theme)
+   ========================================================= */
 @theme inline {
-  --color-background: var(--background);
-  --color-foreground: var(--foreground);
-  --font-sans: var(--font-geist-sans);
+  /* Colori base */
+  --color-background: #ffffff;
+  --color-foreground: #171717;
+
+  /* Font */
+  --font-sans: var(--font-geist-sans), system-ui, -apple-system, BlinkMacSystemFont,
+    "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
   --font-mono: var(--font-geist-mono);
+
+  /* Palette brand iamcavalli — light & clean */
+  --color-primary:      #1a1a1a; /* charcoal per testo principale */
+  --color-secondary:    #666666; /* grigio medio per testo secondario */
+  --color-tertiary:     #999999; /* grigio chiaro per hint e timestamp */
+  --color-bg-subtle:    #f9f9f9; /* grigio molto chiaro per sfondi sezione */
+  --color-border-light: #e5e5e5; /* bordo sottile */
+  --color-accent:       #0066cc; /* blu accent */
+  --color-success:      #16a34a; /* verde per done/saldato */
+  --color-warning:      #ca8a04; /* giallo per in_progress/inviata */
+  --color-info:         #2563eb; /* blu per pending/da_saldare */
 }
 
-@media (prefers-color-scheme: dark) {
-  :root {
-    --background: #0a0a0a;
-    --foreground: #ededed;
-  }
+/* =========================================================
+   Base styles
+   ========================================================= */
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+}
+
+html {
+  scroll-behavior: smooth;
 }
 
 body {
-  background: var(--background);
-  color: var(--foreground);
-  font-family: Arial, Helvetica, sans-serif;
-}
+  background-color: #ffffff;
+  color: #171717;
+  font-family: var(--font-sans);
+  line-height: 1.6;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}