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>

api/admin/invoices-pdf.php

@@ -1,7 +1,7 @@
 <?php
 
 /**
- * BOHA Automation - Invoice PDF Export (Print-ready HTML)
+ * Invoice PDF Export (Print-ready HTML)
  *
  * Generuje HTML fakturu dle vzoru POHODA s QR platebnim kodem (SPAYD).
  * GET /api/admin/invoices-pdf.php?id=X
@@ -361,7 +361,7 @@ try {
     $custDic = $customer ? $esc($customer['vat_id'] ?? '') : '';
 
     // Dodavatel
-    $suppName = $esc($settings['company_name'] ?? 'BOHA Automation s.r.o.');
+    $suppName = $esc($settings['company_name'] ?? '');
     $suppStreet = $esc($settings['street'] ?? '');
     $suppCity = trim(($settings['postal_code'] ?? '') . ' ' . ($settings['city'] ?? ''));
     $suppCountry = $esc($settings['country'] ?? 'Česká republika');

api/admin/offers-pdf.php

@@ -1,7 +1,7 @@
 <?php
 
 /**
- * BOHA Automation - Offers PDF Export (Print-ready HTML)
+ * Offers PDF Export (Print-ready HTML)
  *
  * Returns a self-contained HTML page that auto-triggers window.print().
  * The browser's "Save as PDF" produces the final PDF.

api/admin/totp.php

@@ -1,7 +1,7 @@
 <?php
 
 /**
- * BOHA Automation - TOTP 2FA API
+ * TOTP 2FA API
  *
  * GET  ?action=status           - 2FA status
  * POST ?action=setup            - generovat secret + QR