feat: mobilni responsivita, testy, klavesove zkratky, drag & drop, univerzalizace

- Mobile responsive CSS (touch targets 44px, iOS anti-zoom, reduced motion)
- Vitest setup s 39 testy (formatters, attendanceHelpers, useTableSort)
- Klavesove zkratky (Shift+? napoveda, Ctrl+S ulozit, navigace)
- Drag & drop pro polozky nabidek (@dnd-kit, SortableRow, useSortableList)
- Univerzalizace: odstraneni BOHA brandingu z UI, emailu, PDF
- Smazany nepotrebne soubory (deploy.sh, AUTH_SYSTEM.md, example_design, .htaccess)
- CORS konfigurovatelny pres env promennou

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

package.json

@@ -8,9 +8,15 @@
     "build": "vite build",
     "preview": "vite preview",
     "deploy": "bash deploy.sh",
-    "lint": "eslint src/"
+    "lint": "eslint src/",
+    "test": "vitest run",
+    "test:watch": "vitest"
   },
   "dependencies": {
+    "@dnd-kit/core": "^6.3.1",
+    "@dnd-kit/modifiers": "^9.0.0",
+    "@dnd-kit/sortable": "^10.0.0",
+    "@dnd-kit/utilities": "^3.2.2",
     "date-fns": "^4.1.0",
     "dompurify": "^3.3.1",
     "framer-motion": "^12.23.25",
@@ -23,11 +29,16 @@
   },
   "devDependencies": {
     "@eslint/js": "^10.0.1",
+    "@testing-library/dom": "^10.4.1",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
     "@vitejs/plugin-react": "^4.7.0",
     "eslint": "^10.0.2",
     "eslint-plugin-react-hooks": "^5.2.0",
     "eslint-plugin-react-refresh": "^0.5.2",
     "globals": "^17.4.0",
-    "vite": "^5.4.11"
+    "jsdom": "^28.1.0",
+    "vite": "^5.4.11",
+    "vitest": "^4.0.18"
   }
 }