feat(binary): add full binary simulator with unsigned and two’s complement modes

- Introduce new Binary Simulator page with adjustable bit width (4–16 bits)
- Support unsigned and two’s complement representations with live conversion
- Add left/right shift operations and custom binary/denary input
- Implement accessible bulb-and-switch UI with MD3-inspired styling
- Add seven-segment display font assets for realistic number output
- Establish shared base layout, styles, and tooling for future simulators

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

public/js/binary/unsigned-binary.js

@@ -0,0 +1,115 @@
+// Browser-only script. Safe because it's loaded via <script> (not server-imported).
+
+const BIT_COUNT = 8; // unsigned page = 8 bits
+const bitValues = [128, 64, 32, 16, 8, 4, 2, 1];
+
+const elDenary = document.getElementById("denaryNumber");
+const elBinary = document.getElementById("binaryNumber");
+const elSwitches = document.getElementById("bitSwitches");
+
+const btnCustomDenary = document.getElementById("btnCustomDenary");
+const btnCustomBinary = document.getElementById("btnCustomBinary");
+const btnReset = document.getElementById("btnReset");
+
+let bits = new Array(BIT_COUNT).fill(false);
+
+function renderSwitches() {
+  elSwitches.innerHTML = "";
+
+  bitValues.forEach((value, index) => {
+    const id = `bit-${value}`;
+
+    const wrapper = document.createElement("div");
+    wrapper.className = "switch-col";
+
+    const labelTop = document.createElement("div");
+    labelTop.className = "bit-label";
+    labelTop.textContent = value;
+
+    const label = document.createElement("label");
+    label.className = "rocker";
+    label.setAttribute("for", id);
+
+    const input = document.createElement("input");
+    input.type = "checkbox";
+    input.id = id;
+    input.checked = bits[index];
+
+    input.addEventListener("change", () => {
+      bits[index] = input.checked;
+      updateNumbers();
+    });
+
+    const span = document.createElement("span");
+    span.className = "rocker-body";
+    span.setAttribute("aria-hidden", "true");
+
+    label.appendChild(input);
+    label.appendChild(span);
+
+    wrapper.appendChild(labelTop);
+    wrapper.appendChild(label);
+
+    elSwitches.appendChild(wrapper);
+  });
+}
+
+function updateNumbers() {
+  const binary = bits.map(b => (b ? "1" : "0")).join("");
+  const denary = bits.reduce((acc, b, i) => acc + (b ? bitValues[i] : 0), 0);
+
+  elBinary.textContent = binary;
+  elDenary.textContent = denary.toString();
+}
+
+function resetAll() {
+  bits = new Array(BIT_COUNT).fill(false);
+  renderSwitches();
+  updateNumbers();
+}
+
+function requestCustomDenary() {
+  let input = prompt(`Enter a denary number (0 to 255):`);
+  if (input === null) return;
+
+  const n = Number.parseInt(input, 10);
+  if (Number.isNaN(n) || n < 0 || n > 255) {
+    alert("Invalid input. Enter a number from 0 to 255.");
+    return;
+  }
+
+  let remaining = n;
+  bits = bitValues.map(v => {
+    if (remaining >= v) {
+      remaining -= v;
+      return true;
+    }
+    return false;
+  });
+
+  renderSwitches();
+  updateNumbers();
+}
+
+function requestCustomBinary() {
+  let input = prompt(`Enter an ${BIT_COUNT}-bit binary number (e.g. 01010101):`);
+  if (input === null) return;
+
+  input = input.trim();
+  const re = new RegExp(`^[01]{${BIT_COUNT}}$`);
+  if (!re.test(input)) {
+    alert(`Invalid input. Enter exactly ${BIT_COUNT} digits using only 0 or 1.`);
+    return;
+  }
+
+  bits = input.split("").map(c => c === "1");
+  renderSwitches();
+  updateNumbers();
+}
+
+btnCustomDenary?.addEventListener("click", requestCustomDenary);
+btnCustomBinary?.addEventListener("click", requestCustomBinary);
+btnReset?.addEventListener("click", resetAll);
+
+renderSwitches();
+updateNumbers();