Initial commit

**Motivations:**
- Initialisation du versionning git pour le projet

**Root causes:**
- N/A (Nouveau projet)

**Correctifs:**
- N/A

**Evolutions:**
- Structure initiale du projet
- Ajout du .gitignore

**Pages affectées:**
- Tous les fichiers

web/js/weighted-random.js

@@ -0,0 +1,33 @@
+/**
+ * Seeded RNG (mulberry32) for deterministic hatch results.
+ * @param {number} seed
+ * @returns {() => number}
+ */
+export function createSeededRng(seed) {
+  let state = seed >>> 0;
+  return function next() {
+    state = (state + 0x6d2b79f5) >>> 0; // 32-bit
+    let t = state;
+    t = Math.imul(t ^ (t >>> 15), t | 1);
+    t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
+    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
+  };
+}
+
+/**
+ * @param {() => number} rng
+ * @param {Array<{ id: string, weight: number }>} entries
+ * @returns {string}
+ */
+export function pickId(rng, entries) {
+  let total = 0;
+  for (const e of entries) total += e.weight;
+  if (total <= 0) throw new Error("WeightedRandom: non-positive total weight");
+  const roll = rng() * total;
+  let cumulative = 0;
+  for (const e of entries) {
+    cumulative += e.weight;
+    if (roll < cumulative) return e.id;
+  }
+  return entries[entries.length - 1].id;
+}