feat: add React frontend - homepage, auth, products, craftsmen pages

- React 18 + Vite + TypeScript + TailwindCSS + shadcn/ui components
- Auth pages (login/register) with JWT token management via Zustand store
- Homepage with 9 craft category tiles (ceramics first, lacquerware second)
- METI 伝統的工芸品 badge and featured section on homepage
- Products page with category filters + METI認定 filter
- Craftsmen list page with METI badge display
- Navbar with auth-aware navigation
- Japanese warm color theme (amber/terracotta)
- API proxy config pointing to Express backend

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/tsconfig.json

@@ -0,0 +1,25 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "useDefineForClassFields": true,
+    "lib": ["ES2020", "DOM", "DOM.Iterable"],
+    "module": "ESNext",
+    "skipLibCheck": true,
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "jsx": "react-jsx",
+    "strict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noFallthroughCasesInSwitch": true,
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["./src/*"]
+    }
+  },
+  "include": ["src"],
+  "references": [{ "path": "./tsconfig.node.json" }]
+}