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/includes/Mailer.php

@@ -1,7 +1,7 @@
 <?php
 
 /**
- * BOHA Automation - Email Helper
+ * Email Helper
  *
  * Sends emails via PHP mail() function.
  * Configuration via .env variables.
@@ -23,7 +23,7 @@ class Mailer
     public static function send(string $to, string $subject, string $htmlBody, ?string $replyTo = null): bool
     {
         $fromEmail = env('SMTP_FROM_EMAIL', env('CONTACT_EMAIL_FROM', 'web@boha-automation.cz'));
-        $fromName  = env('SMTP_FROM_NAME', 'BOHA Automation');
+        $fromName  = env('SMTP_FROM_NAME', 'System');
 
         $encodedSubject = '=?UTF-8?B?' . base64_encode($subject) . '?=';