Rebrand to QRForge (local only - do not push before domain confirmed)

Applies the approved QRForge brand kit throughout the app:
- New logo/icon SVGs, favicon set (ico/svg/png), apple-touch-icon, all
  copied from the approved brand kit into src/dist/img/brand/. Old
  Symbol_WhiteBlue.png/DynamicQRCode_Original.png removed (unused after
  the swap).
- Sidebar brand image/text, login and change-password page logos, all
  <title> tags, manifest.json name/theme-color, and the PWA icons
  (dist/img/icon-192.png/icon-512.png, same filenames so no other
  reference needed to change) updated to QRForge branding and the
  #2563EB brand blue.
- New about.php page (+ sidebar link): credits the original upstream
  fork (Giandonato Inverso) and chillerlan/php-qrcode, links to the free
  qr.ensembia.com try-out, the commercial www.qrforge.eu product page,
  and this GitHub repo for self-hosters.
- Footer now reads "QRForge" + "About / credits" + "Version 3.0"
  (replaces the inherited "PHP Qrcode Generator by Giandonato Inverso" /
  "Version 2.3.0" line - full credit moved to the About page instead).
- README.md rewritten: current feature set (all 16 static qr types,
  presets, scanner, PWA, location search, roles), qr.ensembia.com as the
  free try-out, www.qrforge.eu as the commercial product page, corrected
  Docker Compose setup steps (.env is required now, the old README still
  described the single-file demo setup from the original upstream fork).

IMPORTANT: not pushed to origin/gitea. Per user instruction, no push
until qrforge.eu domain registration is confirmed.

src/includes/footer.php

@@ -6,9 +6,10 @@
 
   <!-- Main Footer -->
   <footer class="main-footer text-sm">
-    <strong><a href="https://github.com/giandonatoinverso/PHP-Dynamic-Qr-code" target="_blank">PHP Qrcode Generator</a> by </strong> Giandonato Inverso
+    <strong><a href="https://www.qrforge.eu" target="_blank">QRForge</a></strong> -
+    <a href="./about.php">About</a> / credits
     <div class="float-right d-none d-sm-inline-block">
-      <b>Version</b> 2.3.0
+      <b>Version</b> 3.0
     </div>
   </footer>
 </div>