refactor: scaffold shadcn/ui on the existing Tailwind v3 setup

Adds components.json, cn() util, Radix + cva/clsx/tailwind-merge/
lucide-react/sonner deps, and CSS-variable color tokens mapped onto
the brand's existing pink-500 primary (#ec4899) and neutral grays.

`shadcn init` defaulted to Tailwind v4-style output (oklch colors,
`@theme`-driven CSS, `tw-animate-css`) without updating
tailwind.config.ts, which would not have compiled against the
project's pinned Tailwind v3. Hand-wrote the classic v3 integration
instead (HSL vars + tailwind.config.ts color/radius mapping +
tailwindcss-animate) rather than pull in an unplanned Tailwind
major-version migration.

Also drops the sunset/neon/pastel raw color scales from
tailwind.config.ts: grep confirmed no class ever referenced them,
they were leftover from before lib/themes.ts.

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

tailwind.config.ts

@@ -1,6 +1,8 @@
 import type { Config } from 'tailwindcss';
+import tailwindcssAnimate from 'tailwindcss-animate';
 
 const config: Config = {
+  darkMode: ['class'],
   content: [
     './src/pages/**/*.{js,ts,jsx,tsx,mdx}',
     './src/components/**/*.{js,ts,jsx,tsx,mdx}',
@@ -14,39 +16,52 @@ const config: Config = {
         display: ['var(--font-poppins)', 'system-ui', 'sans-serif'],
       },
       colors: {
-        sunset: {
-          50: '#fff7ed',
-          100: '#ffedd5',
-          200: '#fed7aa',
-          300: '#fdba74',
-          400: '#fb923c',
-          500: '#f97316',
-          600: '#ea580c',
+        border: 'hsl(var(--border))',
+        input: 'hsl(var(--input))',
+        ring: 'hsl(var(--ring))',
+        background: 'hsl(var(--background))',
+        foreground: 'hsl(var(--foreground))',
+        primary: {
+          DEFAULT: 'hsl(var(--primary))',
+          foreground: 'hsl(var(--primary-foreground))',
         },
-        neon: {
-          50: '#f0fdf4',
-          100: '#dcfce7',
-          200: '#bbf7d0',
-          300: '#86efac',
-          400: '#4ade80',
-          500: '#22c55e',
-          600: '#16a34a',
+        secondary: {
+          DEFAULT: 'hsl(var(--secondary))',
+          foreground: 'hsl(var(--secondary-foreground))',
         },
-        pastel: {
-          50: '#fdf4ff',
-          100: '#fae8ff',
-          200: '#f5d0fe',
-          300: '#f0abfc',
-          400: '#e879f9',
-          500: '#d946ef',
-          600: '#c026d3',
+        destructive: {
+          DEFAULT: 'hsl(var(--destructive))',
+          foreground: 'hsl(var(--destructive-foreground))',
         },
+        muted: {
+          DEFAULT: 'hsl(var(--muted))',
+          foreground: 'hsl(var(--muted-foreground))',
+        },
+        accent: {
+          DEFAULT: 'hsl(var(--accent))',
+          foreground: 'hsl(var(--accent-foreground))',
+        },
+        popover: {
+          DEFAULT: 'hsl(var(--popover))',
+          foreground: 'hsl(var(--popover-foreground))',
+        },
+        card: {
+          DEFAULT: 'hsl(var(--card))',
+          foreground: 'hsl(var(--card-foreground))',
+        },
+      },
+      borderRadius: {
+        lg: 'var(--radius)',
+        md: 'calc(var(--radius) - 2px)',
+        sm: 'calc(var(--radius) - 4px)',
       },
       animation: {
         'bounce-slow': 'bounce 2s infinite',
         'pulse-slow': 'pulse 3s infinite',
-        'float': 'float 3s ease-in-out infinite',
-        'wiggle': 'wiggle 0.5s ease-in-out',
+        float: 'float 3s ease-in-out infinite',
+        wiggle: 'wiggle 0.5s ease-in-out',
+        'accordion-down': 'accordion-down 0.2s ease-out',
+        'accordion-up': 'accordion-up 0.2s ease-out',
       },
       keyframes: {
         float: {
@@ -57,10 +72,18 @@ const config: Config = {
           '0%, 100%': { transform: 'rotate(-3deg)' },
           '50%': { transform: 'rotate(3deg)' },
         },
+        'accordion-down': {
+          from: { height: '0' },
+          to: { height: 'var(--radix-accordion-content-height)' },
+        },
+        'accordion-up': {
+          from: { height: 'var(--radix-accordion-content-height)' },
+          to: { height: '0' },
+        },
       },
     },
   },
-  plugins: [],
+  plugins: [tailwindcssAnimate],
 };
 
 export default config;