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/dist/img/brand/icon.svg

@@ -0,0 +1,11 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 151.74 151.74" role="img" aria-labelledby="qfi-title qfi-desc">
+  <title id="qfi-title">QRForge icon</title>
+  <desc id="qfi-desc">QR-block mark with outbound arrow tile.</desc>
+  <g transform="translate(-8.95,-2.57)">
+    <rect id="block-top-left" x="5.24" y="16.81" width="42.29" height="40.70" rx="2.5" fill="#334155" />
+    <rect id="block-mid" x="59.57" y="68.79" width="24.90" height="23.46" rx="2.5" fill="#334155" />
+    <rect id="block-bottom-right" x="96.08" y="103.32" width="40.59" height="31.68" rx="2.5" fill="#334155" />
+    <path id="block-bottom-left-L" d="M 5.24,71.29 Q 5.24,68.79 7.74,68.79 L 45.03,68.79 Q 47.53,68.79 47.53,71.29 L 47.53,103.32 Q 47.53,103.32 47.53,103.32 L 81.97,103.32 Q 84.47,103.32 84.47,105.82 L 84.47,132.50 Q 84.47,135.00 81.97,135.00 L 7.74,135.00 Q 5.24,135.00 5.24,132.50 Z" fill="#334155" />
+    <path id="arrow-tile" d="M 105.68,6.94 Q 104.67,5.88 106.13,5.88 L 145.89,5.88 Q 148.39,5.88 148.39,8.38 L 148.39,44.14 Q 148.39,46.64 146.42,45.11 L 133.00,34.67 Q 133.00,34.67 133.00,34.67 L 112.50,56.87 Q 112.50,56.87 112.50,56.87 L 134.08,56.87 Q 136.58,56.87 136.58,59.37 L 136.58,89.50 Q 136.58,92.00 134.08,92.00 L 98.63,92.00 Q 96.13,92.00 96.13,89.50 L 96.13,56.87 Q 96.13,56.87 96.13,56.87 L 62.10,56.87 Q 59.60,56.87 59.60,54.37 L 59.60,19.60 Q 59.60,17.10 62.10,17.10 L 93.63,17.10 Q 96.13,17.10 96.13,19.60 L 96.13,41.00 Q 96.13,41.00 96.13,41.00 L 97.00,42.17 Q 97.00,42.17 97.00,42.17 L 117.19,22.73 Q 118.99,21.00 117.27,19.18 L 107.68,9.06 Q 106.68,8.00 105.68,6.94 Z" fill="#2563EB" />
+  </g>
+</svg>