feat: setup full Next.js toolchain and core dependencies

- Add runtime deps: react-query, react-hook-form+zod, zustand, ky, openapi-fetch,
  better-auth, react-markdown, shiki, recharts, next-themes, nuqs, sonner, cmdk,
  vaul, embla-carousel-react, motion, date-fns, tailwind-merge, clsx, cva
- Add dev tooling: vitest, testing-library, playwright, prettier(+tailwind plugin),
  husky, lint-staged, jsdom
- Wire providers (QueryClient, Theme, NuqsAdapter, Tooltip, Sonner) into layout
- Add vitest/playwright/prettier configs + lint-staged pre-commit hook
- Add lib/query-client + lib/http (ky) helpers and sample unit test
- Fix react-hooks/set-state-in-effect lint errors (use-mobile useSyncExternalStore,
  carousel async init)
- Remove committed Next-generated types/ duplicates (regenerated under .next/types)

components/ui/toggle.tsx

@@ -0,0 +1,44 @@
+"use client";
+
+import { Toggle as TogglePrimitive } from "@base-ui/react/toggle";
+import { cva, type VariantProps } from "class-variance-authority";
+import { cn } from "cn";
+
+const toggleVariants = cva(
+  "group/toggle inline-flex items-center justify-center gap-1 rounded-lg text-sm font-medium whitespace-nowrap transition-all outline-none hover:bg-muted hover:text-foreground focus-visible:border-ring focus-visible:ring-[3px] focus-visible:ring-ring/50 disabled:pointer-events-none disabled:opacity-50 aria-invalid:border-destructive aria-invalid:ring-destructive/20 aria-pressed:bg-muted data-[state=on]:bg-muted dark:aria-invalid:ring-destructive/40 [&_svg]:pointer-events-none [&_svg]:shrink-0 [Line truncated
+  {
+    variants: {
+      variant: {
+        default: "bg-transparent",
+        outline: "border border-input bg-transparent hover:bg-muted",
+      },
+      size: {
+        default:
+          "h-8 min-w-8 px-2.5 has-data-[icon=inline-end]:pr-2 has-data-[icon=inline-start]:pl-2",
+        sm: "h-7 min-w-7 rounded-[min(var(--radius-md),12px)] px-2.5 text-[0.8rem] has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 [&_svg:not([class*='size-'])]:size-3.5",
+        lg: "h-9 min-w-9 px-2.5 has-data-[icon=inline-end]:pr-2 has-data-[icon=inline-start]:pl-2",
+      },
+    },
+    defaultVariants: {
+      variant: "default",
+      size: "default",
+    },
+  }
+);
+
+function Toggle({
+  className,
+  variant = "default",
+  size = "default",
+  ...props
+}: TogglePrimitive.Props & VariantProps<typeof toggleVariants>) {
+  return (
+    <TogglePrimitive
+      data-slot="toggle"
+      className={cn(toggleVariants({ variant, size, className }))}
+      {...props}
+    />
+  );
+}
+
+export { Toggle, toggleVariants };