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>

vite.config.js

@@ -58,6 +58,11 @@ import { defineConfig } from 'vite'
 
   export default defineConfig({
     plugins: [react(), copyFoldersPlugin()],
+    test: {
+      globals: true,
+      environment: 'jsdom',
+      setupFiles: './src/test/setup.js',
+    },
     build: {
       outDir: 'dist',
       emptyOutDir: true,