feat: initial Next.js 15 implementation with TypeScript and Tailwind CSS 4

Add complete project structure and foundation:

**Core Setup:**
- Next.js 15.5.6 with App Router and React 19
- TypeScript 5.7 with strict mode
- Tailwind CSS 4.1 with custom theme configuration
- ESLint and Prettier configuration

**Dependencies Installed:**
- @tanstack/react-query - Server state management
- zustand - Client state management
- framer-motion - Animations
- lucide-react - Icon library
- react-colorful - Color picker component
- cmdk - Command palette
- sonner - Toast notifications
- clsx + tailwind-merge - Class name utilities

**Project Structure:**
- app/ - Next.js App Router pages
- components/ - React components (ui, color, tools, layout, providers)
- lib/ - Utilities, API client, hooks, stores, constants
- tests/ - Unit and E2E test directories

**API Integration:**
- Type-safe Pastel API client with all 21 endpoints
- Complete TypeScript type definitions for requests/responses
- Error handling and response types

**UI Components:**
- Button component with variants (default, outline, ghost, destructive)
- Input component with focus states
- Providers wrapper (React Query, Toast)
- Root layout with Inter font and metadata

**Pages:**
- Home page with gradient hero and feature cards
- Links to playground and palette generation (pages pending)

**Configuration:**
- Tailwind with HSL color variables for theming
- Dark/light mode CSS variables
- Custom animations (fade-in, slide-up, slide-down)
- @tailwindcss/forms and @tailwindcss/typography plugins

Build successful: 102 kB First Load JS, static generation working.

Ready for color components and playground implementation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

lib/api/types.ts

@@ -0,0 +1,245 @@
+// API Response Types
+export interface SuccessResponse<T> {
+  success: true;
+  data: T;
+}
+
+export interface ErrorResponse {
+  success: false;
+  error: {
+    code: string;
+    message: string;
+    details?: string;
+  };
+}
+
+export type ApiResponse<T> = SuccessResponse<T> | ErrorResponse;
+
+// Color Component Types
+export interface RGBColor {
+  r: number;
+  g: number;
+  b: number;
+  a?: number;
+}
+
+export interface HSLColor {
+  h: number;
+  s: number;
+  l: number;
+  a?: number;
+}
+
+export interface HSVColor {
+  h: number;
+  s: number;
+  v: number;
+}
+
+export interface LabColor {
+  l: number;
+  a: number;
+  b: number;
+}
+
+export interface OkLabColor {
+  l: number;
+  a: number;
+  b: number;
+}
+
+export interface LCHColor {
+  l: number;
+  c: number;
+  h: number;
+}
+
+export interface OkLCHColor {
+  l: number;
+  c: number;
+  h: number;
+}
+
+export interface CMYKColor {
+  c: number;
+  m: number;
+  y: number;
+  k: number;
+}
+
+// Color Information
+export interface ColorInfo {
+  input: string;
+  hex: string;
+  rgb: RGBColor;
+  hsl: HSLColor;
+  hsv: HSVColor;
+  lab: LabColor;
+  oklab: OkLabColor;
+  lch: LCHColor;
+  oklch: OkLCHColor;
+  cmyk: CMYKColor;
+  gray?: number;
+  brightness: number;
+  luminance: number;
+  is_light: boolean;
+  name?: string;
+  distance_to_named?: number;
+}
+
+// Request/Response Types for Each Endpoint
+export interface ColorInfoRequest {
+  colors: string[];
+}
+
+export interface ColorInfoData {
+  colors: ColorInfo[];
+}
+
+export interface ConvertFormatRequest {
+  colors: string[];
+  format: 'hex' | 'rgb' | 'hsl' | 'hsv' | 'lab' | 'oklab' | 'lch' | 'oklch' | 'cmyk' | 'gray';
+}
+
+export interface ConvertFormatData {
+  conversions: Array<{
+    input: string;
+    output: string;
+  }>;
+}
+
+export interface ColorManipulationRequest {
+  colors: string[];
+  amount: number;
+}
+
+export interface ColorManipulationData {
+  results: Array<{
+    input: string;
+    output: string;
+  }>;
+}
+
+export interface ColorMixRequest {
+  colors: string[];
+  fraction: number;
+  colorspace?: 'rgb' | 'hsl' | 'hsv' | 'lab' | 'oklab' | 'lch' | 'oklch';
+}
+
+export interface ColorMixData {
+  results: Array<{
+    color1: string;
+    color2: string;
+    mixed: string;
+  }>;
+}
+
+export interface RandomColorsRequest {
+  count: number;
+  strategy?: 'vivid' | 'rgb' | 'gray' | 'lch';
+}
+
+export interface RandomColorsData {
+  colors: string[];
+}
+
+export interface DistinctColorsRequest {
+  count: number;
+  metric?: 'cie76' | 'ciede2000';
+  fixed_colors?: string[];
+}
+
+export interface DistinctColorsData {
+  colors: string[];
+  stats: {
+    min_distance: number;
+    avg_distance: number;
+    generation_time_ms: number;
+  };
+}
+
+export interface GradientRequest {
+  stops: string[];
+  count: number;
+  colorspace?: 'rgb' | 'hsl' | 'hsv' | 'lab' | 'oklab' | 'lch' | 'oklch';
+}
+
+export interface GradientData {
+  colors: string[];
+}
+
+export interface ColorDistanceRequest {
+  color1: string;
+  color2: string;
+  metric: 'cie76' | 'ciede2000';
+}
+
+export interface ColorDistanceData {
+  color1: string;
+  color2: string;
+  distance: number;
+  metric: string;
+}
+
+export interface ColorSortRequest {
+  colors: string[];
+  order: 'hue' | 'brightness' | 'luminance' | 'chroma';
+}
+
+export interface ColorSortData {
+  sorted: string[];
+}
+
+export interface ColorBlindnessRequest {
+  colors: string[];
+  type: 'protanopia' | 'deuteranopia' | 'tritanopia';
+}
+
+export interface ColorBlindnessData {
+  simulations: Array<{
+    original: string;
+    simulated: string;
+  }>;
+}
+
+export interface TextColorRequest {
+  background_colors: string[];
+}
+
+export interface TextColorData {
+  results: Array<{
+    background: string;
+    text_color: string;
+    contrast_ratio: number;
+  }>;
+}
+
+export interface NamedColor {
+  name: string;
+  hex: string;
+}
+
+export interface NamedColorsData {
+  colors: NamedColor[];
+}
+
+export interface NamedColorSearchRequest {
+  query: string;
+}
+
+export interface NamedColorSearchData {
+  results: NamedColor[];
+}
+
+export interface HealthData {
+  status: string;
+  version: string;
+}
+
+export interface CapabilitiesData {
+  endpoints: string[];
+  formats: string[];
+  color_spaces: string[];
+  distance_metrics: string[];
+  colorblindness_types: string[];
+}