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>

components.json

@@ -0,0 +1,25 @@
+{
+  "$schema": "https://ui.shadcn.com/schema.json",
+  "style": "radix-nova",
+  "rsc": true,
+  "tsx": true,
+  "tailwind": {
+    "config": "tailwind.config.ts",
+    "css": "src/app/globals.css",
+    "baseColor": "neutral",
+    "cssVariables": true,
+    "prefix": ""
+  },
+  "iconLibrary": "lucide",
+  "rtl": false,
+  "aliases": {
+    "components": "@/components",
+    "utils": "@/lib/utils",
+    "ui": "@/components/ui",
+    "lib": "@/lib",
+    "hooks": "@/hooks"
+  },
+  "menuColor": "default",
+  "menuAccent": "subtle",
+  "registries": {}
+}