feat(v2-alpha): refactor binary simulator and introduce shared site layout

- Rewrite binary simulator with unified unsigned and two’s complement logic
- Support dynamic bit widths from 4 to 64 with LSB-preserving resizing
- Replace legacy unsigned-only scripts with a single maintainable implementation
- Extract binary styles into dedicated CSS and add global site styling
- Introduce shared header, footer, and base layout components
- Migrate Binary page to BaseLayout and modular assets

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

src/styles/base.css

@@ -1,4 +1,4 @@
-/* src/styles/base.css */
+src/styles/base.css
 @import "./md3-tokens.css";
 html, body{ height:100%; }
 body{

src/styles/md3-tokens.css

@@ -1,4 +1,4 @@
-/* src/styles/md3-tokens.css */
+src/styles/md3-tokens.css
 /* MD3-inspired tokens tuned for education: high readability, clear contrast, calm surfaces */
 :root{
  /* Typography */