feat(rebrand): migrate CS:Box content to Computing:Box branding

- Rebrand UI text, navigation, footer, and metadata to Computing:Box
- Add canonical URLs and updated Open Graph metadata for SEO
- Replace legacy CS:Box imagery with new Computing:Box assets
- Update About page copy to reflect expanded curriculum focus
- Enhance A Level hexadecimal simulator with custom binary input
- Regenerate exported assets and font hashes

Signed-off-by: Alexander Davis <alex@adcm.uk>

export/sitemap.xml

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd">
+    <url>
+        <loc>https://www.computingbox.co.uk/a-level-hexadecimal.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/about.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/and-gate.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/binary.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/gcse-hexadecimal.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/hex-colours.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/nand-gate.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/nor-gate.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/not-gate.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/or-gate.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/projects.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/twos-compliment-binary.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/unsigned-binary.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/xnor-gate.html</loc>
+    </url>
+    <url>
+        <loc>https://www.computingbox.co.uk/xor-gate.html</loc>
+    </url>
+</urlset>