style(design-system): introduce typography scale + extend radius/space tokens

- Add --font-size-xs..4xl, --font-weight-*, --line-height-* tokens to
  src/styles.scss (no typography scale previously existed)
- Add --radius-xs (4px) and --radius-full (999px) to all three theme
  files (dexar/lavero/novo) to cover chip/badge and pill shapes already
  in wide use (41x 999px, 9x 4px across the app) but previously
  hand-written per component
- Apply the new tokens to global base elements (body/h1-h6/p/small),
  the .btn/.mt-*/.mb-*/.p-* utility classes, and the shared
  .item-badge/.item-tag/.item-simple-desc classes
- Extend --space-* scale with --space-2xl (48px) and --space-3xl (64px)
  for section-level gaps

src/styles/themes/lavero.theme.scss

@@ -31,8 +31,10 @@
   --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.08);
   --shadow-lg: 0 12px 40px rgba(253, 115, 0, 0.25);
   
+  --radius-xs: 4px;
   --radius-sm: 8px;
   --radius-md: 12px;
   --radius-lg: 16px;
   --radius-xl: 20px;
+  --radius-full: 999px;
 }