feat: implement missing features and improvements

Add comprehensive feature set and fixes:

**Theme Improvements:**
- Fix theme flickering by adding blocking script in layout
- Prevents FOUC (Flash of Unstyled Content)
- Smooth transitions between light and dark modes

**Tailwind CSS v4 Migration:**
- Convert globals.css to Tailwind CSS v4 format
- Use @import "tailwindcss" instead of @tailwind directives
- Implement @theme block with OkLCH color space
- Add @plugin directives for forms and typography
- Use :root and .dark class-based theming
- Add all custom animations in CSS
- Create postcss.config.mjs with @tailwindcss/postcss

**Dev Environment:**
- Add .env.local with API on port 3001
- Add dev:api and dev:all scripts to package.json
- Create .env for API with port 3001 configuration
- Enable running both UI and API simultaneously

**New Features Implemented:**

1. **Harmony Palettes** (app/palettes/harmony/page.tsx)
   - Generate color harmonies based on color theory
   - Support for 6 harmony types:
     - Monochromatic
     - Analogous (±30°)
     - Complementary (180°)
     - Split-complementary
     - Triadic (120° spacing)
     - Tetradic/Square (90° spacing)
   - Uses complement and rotate API endpoints
   - Export harmonies in multiple formats

2. **Color Blindness Simulator** (app/accessibility/colorblind/page.tsx)
   - Simulate 3 types of color blindness:
     - Protanopia (red-blind, ~1% males)
     - Deuteranopia (green-blind, ~1% males)
     - Tritanopia (blue-blind, rare)
   - Side-by-side comparison of original vs simulated
   - Support for multiple colors (up to 10)
   - Educational information about each type
   - Accessibility tips and best practices

3. **Batch Operations** (app/batch/page.tsx)
   - Process up to 100 colors at once
   - Text input (line-separated or comma-separated)
   - 5 operations supported:
     - Lighten/Darken
     - Saturate/Desaturate
     - Rotate hue
   - Adjustable amount slider
   - Export processed colors
   - Live validation and color count

**API Query Hooks:**
- Add useSimulateColorBlindness hook
- Add useTextColor hook
- Export ColorBlindnessRequest and TextColorRequest types

**Files Added:**
- postcss.config.mjs
- .env.local
- ../pastel-api/.env
- app/accessibility/colorblind/page.tsx
- app/palettes/harmony/page.tsx

**Files Modified:**
- app/globals.css (Tailwind v4 migration)
- app/layout.tsx (theme flicker fix)
- app/batch/page.tsx (functional implementation)
- lib/api/queries.ts (new hooks)
- package.json (dev scripts)
- tailwind.config.ts (simplified, CSS-first)

All features build successfully and are ready for testing.
Development server can now run with API via `pnpm dev:all`.

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

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

package.json

@@ -9,6 +9,8 @@
   "scripts": {
     "dev": "next dev",
     "dev:turbo": "next dev --turbopack",
+    "dev:api": "cd ../pastel-api && cargo run",
+    "dev:all": "pnpm run dev:api & pnpm run dev",
     "build": "next build",
     "start": "next start",
     "lint": "next lint",