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>

public/styles/global.css

@@ -0,0 +1,75 @@
+:root{
+  --bg: #1f2027;
+  --panel: rgba(255,255,255,.04);
+  --text: #e8e8ee;
+  --muted: #a9acb8;
+  --line: rgba(255,255,255,.12);
+}
+
+*{ box-sizing:border-box; }
+
+body{
+  margin:0;
+  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
+  background: var(--bg);
+  color: var(--text);
+}
+
+.site-header{
+  border-bottom: 1px solid var(--line);
+  background: rgba(0,0,0,.12);
+  backdrop-filter: blur(6px);
+}
+
+.site-header__inner{
+  max-width: 1200px;
+  margin: 0 auto;
+  padding: 14px 20px;
+  display:flex;
+  align-items:center;
+  justify-content:space-between;
+  gap:16px;
+}
+
+.brand{
+  text-decoration:none;
+  color: var(--text);
+  font-weight: 900;
+  letter-spacing: .02em;
+}
+
+.nav{
+  display:flex;
+  gap: 14px;
+  flex-wrap:wrap;
+}
+
+.nav a{
+  color: var(--muted);
+  text-decoration:none;
+  font-weight: 700;
+  font-size: 14px;
+}
+.nav a:hover{ color: var(--text); }
+
+.site-main{
+  min-height: calc(100vh - 120px);
+}
+
+.site-footer{
+  border-top: 1px solid var(--line);
+  margin-top: 28px;
+  background: rgba(0,0,0,.10);
+}
+
+.site-footer__inner{
+  max-width: 1200px;
+  margin: 0 auto;
+  padding: 18px 20px;
+  display:flex;
+  justify-content:space-between;
+  gap:12px;
+  flex-wrap:wrap;
+}
+
+.muted{ color: var(--muted); font-size: 13px; }