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>

src/admin/components/ShortcutsHelp.jsx

@@ -0,0 +1,50 @@
+import { useState } from 'react'
+import useKeyboardShortcuts from '../hooks/useKeyboardShortcuts'
+
+const GLOBAL_SHORTCUTS = [
+  { keys: '?', description: 'Zobrazit klávesové zkratky' },
+  { keys: 'Ctrl + N', description: 'Nový záznam' },
+  { keys: 'Ctrl + S', description: 'Uložit' },
+  { keys: 'Escape', description: 'Zavřít modal / zrušit' },
+  { keys: '/', description: 'Hledat' },
+]
+
+export default function ShortcutsHelp() {
+  const [open, setOpen] = useState(false)
+
+  useKeyboardShortcuts([
+    { key: '?', shift: true, handler: () => setOpen(prev => !prev) },
+    { key: 'Escape', handler: () => setOpen(false), when: open },
+  ])
+
+  if (!open) return null
+
+  return (
+    <div className="admin-modal-overlay" onClick={() => setOpen(false)}>
+      <div className="admin-modal" style={{ maxWidth: 420 }} onClick={e => e.stopPropagation()}>
+        <div className="admin-modal-header">
+          <h3>Klávesové zkratky</h3>
+          <button className="admin-modal-close" onClick={() => setOpen(false)}>
+            <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+              <path d="M18 6L6 18M6 6l12 12"/>
+            </svg>
+          </button>
+        </div>
+        <div className="admin-modal-body">
+          <table className="admin-table" style={{ minWidth: 'auto' }}>
+            <tbody>
+              {GLOBAL_SHORTCUTS.map(s => (
+                <tr key={s.keys}>
+                  <td style={{ width: 120 }}>
+                    <kbd className="admin-kbd">{s.keys}</kbd>
+                  </td>
+                  <td>{s.description}</td>
+                </tr>
+              ))}
+            </tbody>
+          </table>
+        </div>
+      </div>
+    </div>
+  )
+}