feat(web): scaffold Next.js 16 dashboard with design system and auth client (#82)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/design-tokens/src/spacing.ts

@@ -0,0 +1,38 @@
+/**
+ * Mosaic Stack spacing scale (in rem).
+ * Based on a 4px grid (0.25rem increments).
+ */
+
+export const spacing = {
+  px: '1px',
+  0: '0',
+  0.5: '0.125rem',
+  1: '0.25rem',
+  1.5: '0.375rem',
+  2: '0.5rem',
+  2.5: '0.625rem',
+  3: '0.75rem',
+  4: '1rem',
+  5: '1.25rem',
+  6: '1.5rem',
+  8: '2rem',
+  10: '2.5rem',
+  12: '3rem',
+  16: '4rem',
+  20: '5rem',
+  24: '6rem',
+  32: '8rem',
+} as const;
+
+export const radius = {
+  none: '0',
+  sm: '0.25rem',
+  md: '0.375rem',
+  lg: '0.5rem',
+  xl: '0.75rem',
+  '2xl': '1rem',
+  full: '9999px',
+} as const;
+
+export type Spacing = typeof spacing;
+export type Radius = typeof radius;